Plow assembly

ABSTRACT

A snow plow having a wing that is rotatably coupled to a side of a primary plow, and configured to rotate about a first axis substantially parallel to the side of the primary plow. A portion of the wing is operable to rotate about a second axis that is non-parallel to the first axis, where the portion is operable to rotate upward about the second axis relative to the ground in response to the wing encountering an obstruction. A snow plow having a receiver coupled to a surface of the primary plow and an actuator coupled to the receiver. The receiver allows the snow plow to move proximally and distally with respect to a vehicle.

TECHNICAL FIELD

The present application relates to a plow for a vehicle, and moreparticularly to a plow with a movable wing and a plow movable withrespect to a vehicle.

BACKGROUND

There are a variety of conventional plow constructions for vehicles. Onetype of conventional plow configuration is a back-blade style of plowhaving a main snow plow blade and wings attached to a side edge of themain snow plow blade. The back-blade style of plow may be mounted to arear of a plow vehicle, and may include conventional wings that providea larger plow face in use while being stowable for travel on the road.Another type of plow is a front-blade plow, where the plow may bemounted to the front of a plow vehicle. The front-blade plow may alsoinclude conventional wings like the back-blade plow.

In conventional plows with wings, the wings may be rotated in a limitedmanner about a single axis defined by the side edge of the main snowplow blade, where the wing is limited to rotation from a stowed positionproximal to the sides of the plow vehicle to a position parallel to themain snow plow blade. This configuration, as mentioned above, allows aplow operator to position the wings proximal to the sides of the plowvehicle in order to operate the vehicle on a municipal road and withinthe lane constraints of the municipal road. Conventionally, once thevehicle arrives at the site to be plowed, the operator actuates thewings of the plow to a position parallel to the main snow plow blade ora fully extended position, forming a plow face or plow area that isgreater than would otherwise be possible without failing to comply withthe lane constraints of a municipal road.

In practice, the conventional plow with the wings in the fully extendedposition is likely to encounter an obstruction at least once during theoperational life of the plow. Driveways and parking lots can includeobstructions that are concealed by snow that the plow operator cannotsee. As a result, the conventional plow may include control arms andsprings coupled between the plow vehicle mount and the plow that allowthe plow to tilt in response to encountering an obstruction. Thistilting action can prevent damage to the plow in response toencountering the obstruction; however, the plow control arms and springsare limited in degree of titling action provided to a single axis

SUMMARY OF THE DESCRIPTION

The present disclosure is directed to a snow plow having a wing that isrotatably coupled to a side of a primary plow, and configured to rotateabout a first axis substantially parallel to the side of the primaryplow. A portion of the wing is operable to rotate about a second axisthat is non-parallel to the first axis, where the portion is operable torotate upward about the second axis relative to the ground in responseto the wing encountering an obstruction.

In one embodiment, the snow plow includes a primary plow and a firstwing. The primary plow may include first and second sides opposite eachother with a blade disposed between the first and second sides. Theblade may be operable to contact a ground surface to facilitate movingsnow.

In one embodiment, the first wing is rotatably coupled to the first sideof the primary plow via a first connection, and configured to rotateabout a first axis substantially parallel to the first side of theprimary plow. The first wing may include a main wing portion operable torotate about a second axis that is non-parallel to the first axis, wherethe main wing portion is operable to rotate upward about the second axisrelative to the ground in response to the first wing encountering anobstruction.

In one embodiment, the first wing may include a secondary portionoperably coupled to the first side of the primary plow via the firstconnection. The secondary portion may be connected to the main wingportion via a lower connector and an upper connector. The lowerconnector may include a pivotable connection to the secondary portionand a fixed connection to the main wing portion, thereby enabling themain wing portion to rotate about the pivotable connection, wherein thepivotable connection defines the second axis.

In one embodiment, the upper connector includes first and second springsthat oppose each other in compression, where a position of equilibriumbetween the first and second springs corresponds to a primary operatingposition of the first wing relative to the primary plow, wherein thefirst spring enables upward rotation of the main wing portion inresponse to the first wing encountering an obstruction that exerts anupward force on the main wing portion.

In one embodiment, the upper connector includes a hydraulic actuatoroperable to rotate the main wing portion upward and downward about thesecond axis in response to respective retraction and extension of thehydraulic actuator.

In one embodiment, the hydraulic actuator is operably coupled to anadjustable relief valve configured to enable the hydraulic actuator toretract in response to application of force on the main wing portion ina direction perpendicular to the second axis and greater than athreshold trip force.

In one embodiment, a first wing blade is rotatably coupled to the firstwing such that the first wing blade is able to rotate upward in responseto the first wing blade encountering an obstruction that exerts asufficient force on the first wing blade (e.g., a force greater than athreshold force).

In one embodiment, a hydraulic actuator is operably coupled to the firstwing blade to control the wing and enable it to rotate upward inresponse to encountering an obstruction or in response to a command froman operator.

The present disclosure is also directed to a receiver that movablycouples the snow plow to the mounting device attached to the plowvehicle. In one embodiment, the receiver may be coupled to at least onehydraulic actuator and movably coupled to a receiver interface extendingfrom the surface of the snow plow. As the hydraulic actuator(s) move thereceiver interface in and out of the receiver, the distance proximallyand distally between the snow plow and the plow vehicle changes.

These and other advantages and features of the invention will be morefully understood and appreciated by reference to the description of thecurrent embodiment and the drawings.

Before the embodiments of the invention are explained in detail, it isto be understood that the invention is not limited to the details ofoperation or to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention may be implemented in various other embodimentsand of being practiced or being carried out in alternative ways notexpressly disclosed herein. Also, it is to be understood that thephraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including” and “comprising” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items and equivalents thereof. Further, enumeration may beused in the description of various embodiments. Unless otherwiseexpressly stated, the use of enumeration should not be construed aslimiting the invention to any specific order or number of components.Nor should the use of enumeration be construed as excluding from thescope of the invention any additional steps or components that might becombined with or into the enumerated steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a representative view of a snow plow in accordance with oneembodiment.

FIG. 2 shows a representative view of the snow plow of FIG. 1 .

FIG. 3 shows a perspective view of a snow plow in accordance with oneembodiment.

FIG. 4 shows an enlarged view of FIG. 1 in accordance with oneembodiment.

FIG. 5 shows an alternative embodiment of the snow plow in accordancewith one embodiment.

FIG. 6 shows an alternative embodiment of the snow plow in accordancewith one embodiment.

FIG. 7 shows a control system of the snow plow in accordance with oneembodiment.

FIG. 8 shows a control system of the snow plow in accordance with oneembodiment.

FIG. 9 shows a perspective view of a snow plow in accordance with oneembodiment.

FIG. 10 shows a rear perspective view of a portion of the snow plow ofFIG. 9 .

FIG. 11 shows a method of operation for an actuator of a snow plow inaccordance with one embodiment.

FIG. 12 shows another rear perspective view of a portion of the snowplow of FIG. 9 .

FIG. 13 shows a top view of a system for moving a snow plow proximallyand distally with respect to a vehicle in accordance with oneembodiment.

FIG. 14 shows various modes of operation in accordance with oneembodiment.

FIG. 15 depicts a snow plow in accordance with an alternativeembodiment.

FIG. 16 shows a side view of the snow plow of FIG. 15 .

FIG. 17 shows a side view of the snow plow of FIG. 15 in accordance withone embodiment.

FIG. 18 shows another side view of the snow plow of FIG. 15 inaccordance with one embodiment.

FIG. 19 shows another side view of the snow plow of FIG. 15 inaccordance with one embodiment.

FIG. 20 shows another side view of the snow plow of FIG. 15 inaccordance with one embodiment.

FIG. 21 shows a top view of the snow plow of FIG. 15 .

FIG. 22 shows a rear perspective view of a portion of the snow plow ofFIG. 15 .

FIG. 23 shows a method of operation in accordance with one embodiment.

DESCRIPTION

A snow plow for a vehicle is shown in FIGS. 1-3 , and is generallydesignated 100. The snow plow 100 is described herein in severalembodiments as being a back-blade type of plow disposed proximal to arear of a vehicle 10. The snow plow 100 is further described in severalembodiments as a front-blade type of plow mounted to the front of thevehicle 10. However, it is to be understood that the present disclosureis not so limited. The snow plow 100 includes a primary plow 120 havinga longitudinal axis 103 and first and second respective sides 122, 222.The primary plow 120 may include a mold board 124 and a blade 126operable to displace snow or other debris from a ground surface, such asa driveway or parking lot. It is to be understood that the presentdisclosure, although described in conjunction with a snow plow, is notlimited to a snow plow configured primarily for displacing snow. Forinstance, the snow plow 100 in an alternative embodiment may beconfigured as a general plow or blade (e.g., a bulldozer blade) forprimarily moving debris or objects other than snow (e.g., snow removalmay be an incidental function of the general plow or blade).

In the illustrated embodiments of FIGS. 1-3 , the blade 126 of theprimary plow 120 may be a wearable component that can be replaced as theedge of the blade 126 wears away. Example types of blades include apolymer-based blade, such as a polyurethane blade or a rubber-basedblade, and a metal blade, such as heat treated steel. The blade 126 maybe attached to the mold board 124 in a fixed position such that theblade 126 is stationary. Alternatively, the blade 126 may be attached tothe mold board 124 in a trippable configuration, such that the blade 126remains generally stationary in use until an obstruction is encounteredthat exerts a force on the blade 126 that is greater than a thresholdtrip force, at which point the blade 126 may move (e.g., rotate relativeto a bottom edge of the mold board 124) in order to yield to theobstruction.

The mold board 124 in the illustrated embodiment may be shaped orconfigured in a variety of ways, depending on the application. Forinstance, the mold board 124 in the illustrated embodiment of FIG. 3provides a planar surface for pushing snow. However, the mold board 124may be configured differently, such as having a curved surface forfacilitating rolling the snow off the snow plow 100.

The snow plow 100 described herein in conjunction with severalembodiments includes a first wing 110 including a main wing portion 112movable about 1) a first axis 101 and 2) a second axis 102. The snowplow 100 may include a second wing 210 configured in a manner thatmirrors the first wing 110. Components of the second wing 210 that aresimilar to the first wing 110 are designated with a 200 series referencenumber—e.g., the second wing 210 includes a main wing portion 212similar to the main wing portion 112 of the first wing 110. Accordingly,for purposes of disclosure, the descriptions of the components of thefirst wing 110 are not substantially duplicated to describecorresponding components of the second wing 210.

In one embodiment, movement of the main wing portion 112 about thesecond axis 102 may occur in response to encountering an obstructionthat exerts an upward force on the main wing portion 112, such that themain wing portion 112 may rotate about the second axis 102 in responseto the encounter with the obstruction in order to prevent substantialdamage to the snow plow 100 due to the encounter.

In one embodiment, the main wing portion 112 may be rotated about thefirst axis 101 backward and forward between positions B and F, shown inthe illustrated embodiment of FIG. 2 . As an example, the main wingportion 112 may be rotated in front of or behind the longitudinal axis103 of the primary plow 120. Positions B and F may vary from applicationto application. For instance, in the illustrated embodiment, position Bcorresponds to a position of approximately +90° relative to thelongitudinal axis 103 of the primary plow 120 shown in FIG. 2 , andposition F corresponds to a position of approximately −90° relative tothe longitudinal axis 103 of the primary plow 120. With respect to thesecond wing 210, in the illustrated embodiment, position F correspondsto an angle of approximately −90°, and position B corresponds to anangle of approximately +90°. In the illustrated embodiment, the anglesfor the positions F and B for the second wing 210 are similar to theangles for the positions F and B for the first wing 110, but the rangeof movement for the second wing 210 is different from the range ofmovement for the first wing 110.

Positions F and B correspond to the limits of movement of the main wingportion 112, and may vary depending on the application. It is to beunderstood that an operator may position the main wing portion 112 at alocation between positions F and B in use (e.g., to plow an area or totravel). For instance, the operator may position the main wing portion112 at an angle of 20° in use, and then move the main wing portion 112to position B for travel. It is also noted that the operator mayposition the main wing portion 112 of the first wing 110 at an angledifferent from the position of the main wing portion 212 of the secondwing 210. For instance, the operator may position the main wing portion212 of the second wing 210 at an angle of +200° (or) −160° about thefirst axis 201, and position the main wing portion 112 of the first wing110 at an angle of −20° about the first axis 101, thereby positioningone wing forward of the longitudinal axis 103 and the other wing aft ofthe longitudinal axis 103.

In one embodiment, regardless of the longitudinal axis 103 or theposition and configuration of the primary plow 120, position B maycorrespond to an angle about the first axis 101 that disposes the firstwing 110 in a stowed position such that the main wing portion 112 isgenerally proximal to and parallel to a side of the vehicle to which thesnow plow 100 is mounted. This way, with the first wing 110 in thestowed position, the snow plow 100 may fit within the width constraintsimposed by a municipal road for travel thereon.

The first wing 110 may include a secondary wing portion 116 pivotablycoupled to the primary plow 120 to facilitate rotation of the first wing110 about the first axis 101. The secondary wing portion 116 may bepivotably coupled to the primary plow 120 via a joint 117, which may bedefined by a hinge and pin configuration that is provided between thefirst side 122 and the secondary wing portion 116 and that allowsrotation of the first wing 110 about the first axis 101. The secondarywing portion 116 may be moved via an actuator 114 (e.g., a hydraulicactuator) capable of extending and retracting to rotate the first wing110 between positions F and B about the first axis 101.

In an alternative embodiment, the actuator 114 may be operable to allowthe first wing 110 to pivot toward position B in response toencountering an object that exerts a force greater than a trippingthreshold. For instance, the actuator 114 may be configured to retractin response to a force that is applied on the first wing 110 in adirection normal or perpendicular to the first axis 101 and that isgreater than the tripping threshold. In this way, the first wing 110 maybe configured to yield in response to encountering an obstruction.Example configurations for retracting an actuator 114 in response to anobstruction are described herein, and may be implemented in conjunctionwith the actuator 114; however, it is to be understood that any type oftripping mechanism may be implemented in conjunction with the first wing110 to facilitate yielding in response to encountering significantobstructions.

The first wing 110 may include a wing blade 119, similar in somerespects to the blade 126 of the primary plow 120. For instance, thewing blade 119 may be a wearable blade capable of being replaced whenconsidered appropriate. The wing blade 119 may also be made of materialsimilar to the blade 126 of the primary plow 120, such as being made ofa polymer or metal material. In the illustrated embodiment, the wingblade 119 may be coupled to a mold board portion 111 of the main wingportion 112 in a stationary manner (e.g., via fasteners). Alternatively,similar to an alternative embodiment of the blade 126, the wing blade119 may be coupled to the mold board portion 111 in a manner that allowsthe wing blade 119 to pivot relative to the bottom edge of the moldboard portion 111 in response to encountering an objection that appliesa force on the wing blade 119 that exceeds a threshold tripping force.The threshold may be determined based on a variety of factors,including, for instance, a target amount of force for moving debris,strength of the snow plow 100 and the first wing 110.

The main wing portion 112 of the first wing 110 in the illustratedembodiment of FIG. 1 is operable to rotate about the second axis 102.The main wing portion 112 may be pivotably coupled to the secondary wingportion 116 such that the main wing portion 112 may rotate about thesecond axis 102 between positions U and D shown in the illustratedembodiment of FIG. 1 . Positions U and D may be determined based ontarget operating conditions. For instance, position U may be determinedto be approximately 6 inches of rise with respect to the ground surfaceor the bottom edge of the blade 126 of the primary plow 120. Six inchesin this example is considered sufficient displacement in order to yieldto an obstruction encountered in a driveway or parking lot withoutsignificant damage to the snow plow 100 or vehicle 10. It is noted thatposition U described herein corresponds to an upper limit of movement ofthe main wing portion 112. The main wing portion 112 may be positionedlower than the upper limit corresponding to position U.

The obstruction may be encountered in a variety of ways. For instance,when the first wing 110 is rotated about the first axis 101 at −90° inthe position F, the toe of the first wing 110 may be susceptible toencountering an object. If such an object is encountered in thisposition, the first wing 110, as discussed herein, may rotate upwardabout the second axis 102. Such object may take the form of a curb orparking lot divider.

In an alternative example, the first wing 110 may be rotated about thefirst axis 101 at 0° between positions F and B, and an obstruction maybe encountered by the wing blade 119 that applies an upward force on thefirst wing 110. Such a force, if above a threshold force, may cause themain wing portion 112 to rotate upward as discussed herein.

Turning to position D, the main wing portion 112 may pivot downwardrelative to the second axis 102 to position D, which may vary dependingon the application. In the illustrated embodiment, position Dcorresponds to approximately 3 inches of downward displacement withrespect to the bottom edge of the blade 126 of the primary plow 120.Similar to position U, position D is considered limited with respect tomovement of the main wing portion 112, such that the main wing portion112 may be positioned between positions U and D. Position D, in oneembodiment, may be determined based on the possible extent of wear tothe wing blade 119 (e.g., the difference between a new wing blade 119and a wing blade 119 that is considered to need replacing) and degree ofterrain variation to be encountered by the main wing portion 112.

In one embodiment, undulations or unevenness in a driveway or parkinglot may be encountered by the first wing 110. The main wing portion 112may be biased toward position D, such that contact between the wingblade 119 and the ground is maintained to the extent the undulations arewithin the range between positions U and D.

The connector 150 between the main wing portion 112 and the secondarywing portion 116 of the first wing 110 is shown in further detail in theillustrated embodiment of FIG. 4 . The connector 150 may include anupper connector 140 and a lower connector 130. The lower connector 130may include a plate 132 fixedly connected to the main wing portion 112and pivotably connected to the secondary wing portion 116, enabling themain wing portion 112 to pivot or rotate about the second axis 102.

In the illustrated embodiment, the upper connector 140 of the connector150 may be configured to substantially prevent movement of the main wingportion 112 relative to the secondary wing portion 116 in a directionparallel to the second axis 102. The upper connector 140, on the otherhand, may be configured to allow rotation of the main wing portion 112relative to the secondary wing portion 116 with respect to the secondaxis 102.

The upper connector 140, in the illustrated embodiment, includes firstand second springs 142, 144 and a linkage 141. The linkage 141 may beconnected to an anchor 148 of the secondary wing portion 116 and may beoperable to slide within a slot of a spring interface 147 of the mainwing portion 112.

The first and second springs 142, 144 may be configured to act againsteach other in compression with a balanced position corresponding to atarget position of the lower edge of the wing blade 119 being generallyparallel with the lower edge of the blade 126 of the primary plow 120.The first spring 142 may compress relative to an anchor 148 of thesecondary wing portion 116 and a spring interface 147 of the main wingportion 112, enabling the main wing portion 112 to rotate upward toposition U in response to a force applied upward on the main wingportion 112 that is greater than a threshold force (which depends atleast in part on the stiffness of the first spring 142). In theillustrated embodiment, the second spring 144 may operate in compressionbetween a floating anchor 146 and the spring interface 147, enabling thefirst spring 142 to urge the main wing portion 112 toward position D butnot further than position D. That is, at position D, the first andsecond springs 142, 144 may be in equilibrium, where, in operation andin contact with the ground, the main wing portion 112 may be disposedbetween positions U and D, and where, in a raised position where thesnow plow 100 is lifted off the ground, the main wing portion 112 mayrotate to position D. The first spring 142 and second spring 144 in thisrelationship may operate to urge the wing blade 119 toward the ground tomaintain contact between the ground and the wing blade 119 (despitewear).

It is noted that in the illustrated embodiments of FIGS. 1, 2, and 4 ,the main wing portion 112 is shown with a gap between the sides 113, 115that increases in size from the lower connector 130 to the upperconnector 140. In this configuration, the side 113 of the main wingportion 112 may move closer to the side 115 of the secondary wingportion 116 as the main wing portion 112 moves toward position U and thefirst spring 142 is compressed. Alternatively, as depicted in theillustrated embodiment of FIG. 5 , a first wing 110′ is provided similarin some respects to the first wing 110 with several exceptions,including a main wing portion 112′ having a side 113′ that is proximalto the side 115′ of the secondary wing portion 116′ such that, with thebottom edge of the main wing portion 112′ being substantially parallelto the bottom edge of the secondary wing portion 116′, the gap betweenthe sides 113′, 115′ is substantially the same from between the lowerand upper connectors 130′, 140′. The upper part of the main wing portion112′, proximal to the upper connector 140′, may move behind or in frontof the secondary wing portion 116′ as the main wing portion 112′ rotatesabout the second axis 102.

In an alternative embodiment, depicted in the illustrated embodiment ofFIGS. 6 and 7 , a first wing 110″ is provided similar in some respectsto the first wing 110, 110′ with several exceptions. The first wing 110″may include a main wing portion 112″ with a mold board portion 111″ anda wing blade 119″, similar to the main wing portion 112, mold boardportion 111 and wing blade 119. The first wing 110″ may include a lowerconnector 130″ and an upper connector 140″ that form part of theconnector 150″ that couples the main wing portion 112″ to the secondarywing portion 116″. The lower connector 130″ may be similar to the lowerconnector 130, including a plate 132″ that facilitates rotation of themain wing portion 112″ about the second axis 102.

The upper connector 140″ in the illustrated embodiments of FIGS. 6 and 7may be an actuator 145″ connected to an anchor 148″ of the secondarywing portion 116″ and an anchor 146″ of the main wing portion 112″. Theactuator 145″ may be operable to extend or retract to rotate the mainwing portion 112″ about the second axis 102. In one embodiment, theactuator 145″ may be configured to automatically retract in response toapplication of force above a threshold trip force on the main wingportion 112″ along an axis perpendicular to the second axis 102 (e.g.,an upward force on the wing blade 119″ that occurs in response toencountering an object). Optionally, the actuator 145″ may be configuredto extend to rotate the main wing portion 112″ into contact with theground (within the limit of position D) in response to withdrawal of theforce that was above the threshold force. Additionally, oralternatively, the actuator 145″ may be configured to operate as a typeof spring retracting and extending in response to a force less than thethreshold trip force in a more controlled, gradual, or slower mannerthan in retraction in response to a force greater than the thresholdtrip force.

In the illustrated embodiment of FIG. 7 , the actuator 145″ is ahydraulic actuator having a cylinder side coupled to the anchor 148″ anda rod side coupled to the anchor 146″. A control system 300 may beoperable to direct operation of the actuator 145″, and may include adirectional control valve 302 that, in conjunction with the pilotoperated check valves 308, enables an operator to extend or retract thepiston of the actuator 145″ based on the position of the directionalcontrol valve 302. The directional control valve 302 is shown in theillustrated embodiment with a manual actuator; however, the presentdisclosure is not so limited. The directional control valve 302 may beoperated via an electromechanical controller.

In operation, the directional control valve 302 positioned to connectthe pump side to the cap-end of the actuator 145″ and the rod-end to thetank reservoir. The pilot actuated check valves 308 may allow thehydraulic fluid to flow from the pump 310 such that the rod extends,causing the anchor 146″ to rotate the main wing portion 112″ downwardtoward position D. The relief valve 312 may divert fluid to the tankreservoir in response to the rod of the actuator 145″ dead heading orencountering resistance above a threshold. After the operator hasextended the actuator 145″ to a target position, the directional controlvalve 302 may be positioned to a neutral position, causing the pilotactuated check valves 308 to close in order to maintain pressure withinthe actuator 145″ to maintain the extended position of the actuator145″.

In the illustrated embodiment, the control system 300 includes anadjustable relief valve 306 configured to crack and allow fluid to flowfrom the cylinder-side of the actuator 145″ to the tank reservoir inresponse to pressure greater than a threshold pressure. The thresholdpressure may be determined based on an adjustment of the adjustablerelease valve 306, and may be configured to correspond to a targetthreshold trip force for the actuator 145″. In response to theadjustable relief valve 306 opening, the cylinder side and the rod sideof the actuator 145″ may float, allowing the rod to retract into thecylinder in response to continued application of force above thethreshold trip force. This mode of operation may enable the actuator145″ to allow the main wing portion 112″ to move toward position U inresponse to application of force above the threshold trip force. Aftersuch a force is withdrawn, the operator or control system 300 may directthe actuator 145″ to re-extend for using the first wing 110″ to movesnow.

An alternative embodiment of the control system is shown in FIG. 8 , anddesignated 300′. The control system 300′ may include pilot actuatedcheck valves 308′, a pump 310′, a relief valve 312′, and a directionalcontrol valve 302′ similar to the correspondingly referenced componentsof the control system 300. The adjustable relief valve 306′ in theillustrated embodiment is operable to divert fluid from thecylinder-side of the actuator 145″ to the tank, allowing the actuator145″ to retract in response to application of force greater than thethreshold trip force. The directional control valve 302′ may be left ina position to extend the rod of the actuator 145″ such that after theforce is removed, the rod is extended to an operating position.

In the illustrated embodiment of FIG. 8 , the rod-side flow pathincludes a check valve and a restrictor 305′ operable to allow fluidflow into the rod-side more quickly than out of the rod-side. Thisconfiguration may enable the actuator 145″ to retract more quickly thanit extends.

The snow plow 100 may be coupled to the vehicle 10 in a variety of ways,as discussed herein. The snow plow 100 in the illustrated embodiment ofFIG. 3 is coupled to the vehicle via a hitch system 12. The hitch system12 may interface with the snow plow 100 to enable removable couplingbetween the vehicle 10 and the snow plow 100. As discussed herein, thesnow plow 100 is shown coupled to the rear of the vehicle 10; however,the present disclosure is not so limited. The snow plow 100 may becoupled to the front of the vehicle 10 via a hitch system or vehicleconnection system configured to facilitate such a connection to thefront of the vehicle 10. An example hitch system for the snow plow 100,in one embodiment, is described in U.S. Pat. No. 10,150,428, entitledADAPTABLE HITCH SYSTEM, filed Feb. 19, 2018, issued Dec. 11, 2018, toWeihl—the disclosure of which is hereby incorporated by reference in itsentirety. An example connection system for the snow plow, in oneembodiment, is described in U.S. Patent Application 62/940,590, entitledPLOW ASSEMBLY LINKAGE, filed Nov. 26, 2019, to Weihl—the disclosure ofwhich is hereby incorporated by reference in its entirety.

I. Front Plow

In an alternative embodiment, a snow plow 1000 is a front-blade plow.One embodiment of the snow plow 1000 as a front-blade plow mounted tothe front of the vehicle 10 is depicted in FIG. 9 . The snow plow 1000may be similar to the snow plow 100 described above with the primaryexception of its mounting position on the vehicle 10. However, the snowplow 1000 has some differences from one or more embodiments describedherein. The snow plow 1000 may be coupled to a vehicle support 1412 viaa plow support 1380.

In one embodiment, the snow plow 1000 may include a primary plow 1120coupled to the plow support 1380. The snow plow 1000 may also include afirst wing 1110 and a second wing 1210. The first wing 1110 may berotatably coupled to the primary plow 1120 on a first side 1122 via ajoint 1117. The joint 1117 may vary from application to application, andis depicted as a hinge and pin configuration but the disclosure is notso limited. The joint 1117 allows the first wing 1110 to rotate about anaxis 1101 to position F and position B as described with respect to FIG.2 . However, position F and position B may not be at the same angularpositions as described above and may vary based on the application.Rotation about the axis 1101 allows the first wing 1110 to rotate towardthe vehicle 10 to position B, which may allow the vehicle 10 to fitwithin a standard vehicle lane while travelling. The first wing 1110 canalso rotate away from the vehicle 10 to position F. The first wing 1110may be rotated by an actuator 1114, which is described below withreference to FIG. 10 . In the illustrated embodiment a limiter 1135 isprovided to contact a surface 1139 of the first wing 1110 at one or morelimit positions to prevent further movement. In the illustratedembodiment, the limiter may be configured to interface with the firstwing 1110 at positions F and B to prevent further rotation outside therange between F and B.

Components of the second wing 1210 that are similar to the first wing1110 are designated with a 1200 series reference number—e.g., the secondwing 1210 may rotate about an axis 1201 similar to how the first wing1110 may rotate about an axis 1101. Accordingly, for purposes ofdisclosure, the descriptions of the components of the first wing 1110are not substantially duplicated to describe the correspondingcomponents of the second wing 1210.

The first wing 1110 may include a main wing portion 1112 and a wingblade 1119. The wing blade 1119 may be fixedly connected to the mainwing portion 1112, or the wing blade 1119 may be able to rotate upwards,for example in response to a change in contour of the ground orencountering debris or an obstruction that exerts a force greater than atripping threshold. In one embodiment, the wing blade 1119 may include apivot portion 1118 and a sliding portion 1121. In the depictedembodiment, the sliding portion 1121 includes a fastener seated withinor captured by a channel or slot to allow the wing blade 1119 to moveupward in response to an upward force (e.g., a tripping force or theground in response to a change in surface contour), while maintaining acoupling between the sliding portion 1121 and the main wing portion1112. The wing blade 1119 may rotate about the pivot portion 1118 suchthat the sliding portion 1121 moves from position L to position H. Theposition L may correspond to a position lower than a ground contactingplane 1125 defined by the blade 1126 of the primary plow 1120, andposition H may correspond to a position higher than this groundcontacting plane 1125 defined by the wing blade 1119. In use, theposition of the sliding portion 1121 of the wing blade 1119 may bebetween position L and H with the wing blade 1119 contacting the ground.The position of the sliding portion 1121 may vary as the contour of theground changes. As described herein, the sliding portion 1121 of thewing blade 1119 may be biased toward the ground such that, as the snowplow 1000 travels along the ground and the ground contour lowersrelative to a current position of the sliding portion 1121, the slidingportion 1121 may lower toward position L to follow the contour of theground. Conversely, the sliding portion 1121 may lift toward position Has the ground contour rises as the snow plow 1000 travels over theground and the height of the ground near the sliding portion 1121 isdifferent from the height of the ground near the pivot portion 1118. Thebias force may vary from application to application, and may bedetermined selectable, in operation, installation, or the design stage,or a combination thereof, to enable the sliding portion 1121 of the wingblade 1119 to substantially maintain contact of the wing blade 1119 withthe ground and to allow upward movement in response to changes in groundcontour and/or an encounter with an obstruction.

In one embodiment, a distal portion 1131 of the wing blade 1119 distalfrom the pivot portion 1118 may be angled, (e.g., sloped or ramped) orcurved, which may allow the distal portion 1131 to engage a potentialobstruction and cause the wing blade 1119 to pivot upward toward H inresponse to encountering the obstruction. For instance, the angled orcurved construction of the distal portion 1131 may direct an obstructionunder the wing blade 1119 toward a bottom portion of the main blade 1126so that the plow 1000 ride over the obstruction.

The wing blade 1119 in the illustrated embodiment pivots about an areaproximal to the pivot portion 1118, such that the pivot portion 1118 isnear to or aligned with the plane of the adjacent segment's blade (e.g.,main blade 1126). In response to the distal portion 1131 encountering anobstruction, the distal portion 1131 may begin to ride over theobstruction, causing the wing blade 1119 to pivot upward toward positionH, and allowing the entire undersurface of the wing blade 1119 to rideover the obstruction. In this circumstance, because the undersurface ofthe wing blade 1119 leads to the pivot portion 1118 near or aligned withthe plane of the blade 1126 (e.g., a main blade), the wing blade 1119may raise the blade 1126 to clear the obstruction. As described herein,a movable component capable of pivoting in accordance with one or moreembodiments described in conjunction with the wing blade 1119 may beincorporated into any segment of a plow construction, including segmentsof a V-blade. And although the wing blade 1119 is shown operable topivot relative to an area proximal to a connection to another segment ofa plow, it is to be understood that the wing blade 1119 may pivotrelative to an area distal from a connection to another segment of theplow.

The distance from position L to position H may vary depending on theapplication. In one example, the distance from position L to position Hmay be six inches, with L being two inches lower than the groundcontacting plane 1125, and H being four inches higher than the groundcontacting plane 1125. Six inches in this example is consideredsufficient displacement in order to yield to an obstruction encounteredin a driveway or parking lot without significant damage to the snow plow1000 or vehicle 10, or to follow changes in the contour of the groundwhile maintaining contact with the ground. It is noted that position Hdescribed herein corresponds to an upper limit of movement of the wingblade 1119. Depending on the strength of the tripping force exerted onthe wing blade 1119 and the changes in contour of the ground, thesliding portion 1121 might not move all the way up to position H.

The wing blade 1119 and the blade 1126 are wearable components of thesnow plow 1000, generally meaning that the ground contacting surfaces ofthe wing blade 1119 and the blade 1126 wear away in response to repeatedcontact with the ground. Because the sliding portion 1121 of the wingblade 1119 is biased downward, in one embodiment, despite wear of thewing blade 1119 or the blade 1126, or both, the sliding portion 1121 maybe operable to maintain contact with the ground.

The distance L may vary as the wing blade 1119 wears away near thesliding portion 1121 and the pivot portion 1118 of the wing blade 1119.For instance, as the main blade 1126 wears, the pivot portion 1118 ofthe wing blade 1119 may wear as well, raising the ground contactingplane 1125 over time relative to a new set of blades. The slidingportion 1121 may or may not wear at the same rate as the pivot portion1118 and the blade 1126. However, because the sliding portion 1121 mayraise and lower, despite changes in the ground contacting plane 1125,the sliding portion 1121 may be operable to maintain contact with theground. If the sliding portion 1121 wears away in this configuration,the amount of allowable travel (e.g., L, H, or both) may vary. Thesliding portion 1121 may wear such that L, H, or both, are consideredinsufficient, such as the upward movement capability of H becomesinsufficient to allow the sliding portion 1121 to move upward to trackchanges in ground contour or to move in response to encountering anobstruction. In this case, the wing blade 1119 may be replaced alongwith one or more other blades of the snow plow 1000.

In one embodiment, the wing blade 1119 may be referred to as the mainwing portion and the main wing portion 1112 may be described as asecondary portion of the wing blade 1119. For instance, the first wing1110 and a similarly configured second wing 1210 may be incorporatedinto the snow plow 1000 described herein, with the wing blade 1119 ofthe first wing 1110 being the main wing portion of the snow plow 1000that is capable of pivoting, and the main wing portion 1112 of the firstwing 1110 being the secondary portion of the snow plow 1000 that iscoupled to a first side of the primary plow of the snow plow 1000. Thewing blade 1119 may rotate about a second axis between position L andposition H similar to rotation of the main wing portion 112 of FIGS. 1-6being allowed about the axis 102 between position U and position D. Themain wing portion 1112 may be rotatably coupled to the primary plow 1120similar in rotation of the secondary wing portion 116 of FIGS. 1-6relative to a first side of the primary plow 120 about the axis 101.

Turning to the illustrated embodiment of FIG. 10 , a rear perspectiveview of a portion of the snow plow 1000 is shown. FIG. 10 shows the rearof the first wing 1110 and the primary plow 1120. In one embodiment, thewing blade 1119 may move from position L to position H based on movementof an actuator 1145. In the depicted embodiment, the actuator 1145 is ahydraulic actuator having a cap side 1147 coupled to the main wingportion 1112 and a rod side 1148 coupled to an anchor 1146. The anchor1146 is coupled to the wing blade 1119 and operable to move the wingblade 1119. In the depicted embodiment, the cap side 1147 of theactuator 1145 is filled with a compressible gas (e.g., nitrogen gas),which biases the rod toward an extended position, which is downward inthe illustrated embodiment. An amount of hydraulic fluid on the rod side1148 of the actuator 1145 may be selectively changed, e.g., byincreasing or decreasing the fluid pressure on the rod side 1148. Thehydraulic fluid pressure on the rod side 1148 may be transitioned to afloat mode in which the hydraulic fluid is neither increasing ordecreasing the fluid pressure on the rod side 1148. In this float mode,the compressible gas may extend the actuator 1145 until sufficientresistance is met from either the ground by the wing blade 1119 or amechanical limit of extension of the actuator 1145.

In one embodiment, the cap side 1147 of the actuator 1145 may include anaccumulator (e.g., a reservoir or tank) for the compressible gas. Theaccumulator may be integrated into the cap side 1147 of the actuator1145 or may be external to the actuator 1145. By providing compressiblegas on one side of the actuator 1145, a hydraulic coupling to this sideof the actuator 1145 can be left out or absent from the hydraulicsystem. As a result, in one embodiment, the actuator 1145 may be coupledto only one hydraulic hose 1149 or a single hydraulic coupling. Thegreater the number of hydraulic hoses and couplings, the greater thecomplexity of the system, for installation, operation, and maintenance.With fewer hydraulic hoses and couplings in accordance with oneembodiment, the installation time and maintenance time of the snow plow1000 may be reduced, and operation can be more robust. Conventionalhydraulic systems require more complicated control as operation requiresthat hydraulic fluid is pushed to one side of the cylinder whilesimultaneously being removed from the other. One embodiment according tothe present disclosure may not rely on simultaneous control of fluid onthe rod side 1148 and the cap side 1147 of the actuator 1145.

Although the present disclosure is described in conjunction with the capside 1147 including a compressible gas and biasing the actuator 1145toward an extended position, the present disclosure is not so limited.Alternatively, the rod side 1148 may include a compressible gas(optionally coupled to an external accumulator), and the cap side 1147may be coupled to a hydraulic system for controlling the amount ofhydraulic fluid in the cap side 1147. This alternative construction maybe configured with the compressible gas on the rod side 1148 biasing theactuator 1145 toward a contracted position. As described herein, theactuator 1330 is configured in this manner to facilitate tilting of atop portion of the snow plow 1000 forward about an axis of rotation inresponse to the blade 1126 encountering an obstruction.

In one embodiment, in response to the wing blade 1119 encountering asufficient force to overcome the bias of the actuator 1145 (e.g., atripping force or a change in ground contour), the compressible gas ofthe cap side 1147 of the actuator 1145 may operate as a spring and allowthe rod to move upwards therefore moving the wing blade 1119. Inresponse to a force sufficient to overcome the spring force (e.g., thebias force) of the compressed gas, more hydraulic fluid may flow intothe rod side 1148 of the actuator 1145 while the compressible gascompresses (optionally, compressing in an external accumulator). If theforce is no longer present, the compressible gas may expand from theaccumulator (internal and/or external) back to the cap side 1147 of theactuator 1145, biasing the rod downwards or to an extended position andmoving the wing blade 1119 to maintain contact with the ground. Thefluid on the rod side 1148 may be forced back to the tank of thehydraulic system by the compressible gas with the force no longer beingpresent. The compressible gas may keep or maintain the sliding portion1121 of the wing blade 1119 in contact with the ground (or at a setposition) even while the other portions of the wing blade 1119 wearaway, and even in cases where other portions of the wing blade 1119 areworn such that they are no longer in contact with the ground. It is tobe understood that the actuator 1145 is one example of a trippingmechanism, ground follow mechanism, or bias mechanism to a set position,or any combination thereof, and that any type of tripping mechanism,ground follow mechanism, or bias mechanism may be used in conjunctionwith the wing blade 1119 to facilitate yielding in response toencountering a tripping force and/or in response to forces that overcomethe bias force of the actuator 1145. The hydraulic fluid on the rod side1148 in this example may be provided in a float mode that allows thefluid to readily pass into and out of the rod side 1148 in response tomovement of the actuator 1145.

A control method for the control system in accordance with oneembodiment for operation of the actuator 1145 is shown in FIG. 11 . Themethod 1300 is focused generally toward operation of a system configuredto retract and extend the wing blade 1119. The control system may beconfigured to direct operation of one or more other actuators in asimilar manner.

In addition to the operation of the actuator 1145 described inconjunction with tripping in response to an obstruction and/or movingbased on changes in the ground contour, a control system may be operableto direct operation of the actuator 1145. The control system may providemanual control, electromechanical control, or a combination of the two,over the plow. An operator may control the position of the snow plow1000 by signaling the control system to control the hydraulic fluid inthe system, such as by extending or retracting the lift actuator 1416.If an operator directs the snow plow 1000 to move upward, for example toraise the snow plow 1000 for stacking or transport, the operator maysignal (e.g., provide user input) to the control system to supply morehydraulic fluid to the rod side of the actuator 1416, thus causing therod to retract. The supply of hydraulic fluid to the rod side of theactuator 1416 may also be fluidly coupled to the rod side 1148 of theactuator 1416, such that, in response to providing hydraulic fluid underpressure to the rod side of the actuator 1416, the actuator 1145 for thewing blade 1119 retracts first (compressing the gas) until a mechanicallimit of retraction is reached, and then the lift actuator 1416 raisesand retracts. Steps 1320, 1322, 1324.

Conversely, if the operator provides a signal to the control system tolower the snow plow 1000, the system may supply hydraulic fluid to thecap side of the lift actuator 1416 under pressure and may cause the liftactuator 1416 to extend, and displace fluid from the rod side of thelift actuator 1416 under pressure. Step 1302, 1304, 1306. Because theactuator 1145 is fluidly coupled to the rod side of the lift actuator1416, this pressure on the rod side of the lift actuator 1416 maymaintain the position of the actuator 1145 in the retracted position(with the gas in a compressed state). After the lift actuator 1416 isfully extended such that the snow plow 1000 contacts the ground (or themechanical limit of the lift actuator 1416 is reached), the pressure onthe rod side of the lift actuator 1416 (due to supply of fluid to thecap side) may subside and the actuator 1145 may extend because thecompressed gas in the actuator 1145 is no longer under pressure fromfluid on the rod side 1148 of the actuator 1145. Step 1308, 1310. Inthis way, the actuator 1145 may automatically extend in response to thesnow plow 1000 contacting the ground, and may automatically retract justprior to the snow plow 1000 being raised off the ground.

In other words, at a start 1302, the rod of the actuator 1416 may bedisposed in a retracted position with the plow in an up position (forstacking or transport). The hydraulic pressure on the rod side of theactuator 1416 may also be provided to the rod side 1148 to compress thegas on the cap side 1147 of the actuator 1145, maintaining the wingblade in an up position proximal to position H.

At step 1304, the control system may receive a directive from theoperator to lower the snow plow 1000. Hydraulic fluid may be provided tothe lift actuator 1416 under pressure to cause the lift actuator 1416 toextend. In response, hydraulic fluid may be evacuated from the liftactuator 1416 under pressure, maintaining the actuator 1145 in aretracted position. After the lift actuator 1416 extends the plow to theground position, pressure on the rod side 1148 of the actuator 1145 maysubside, allowing the compressed gas to extend the actuator 1145 to movethe wing blade 1119 into contact with the ground. Step 1310. Thecompressed gas may bias the wing blade 1119 toward ground contact, andmay allow the wing blade 1119 to move upward automatically in responseto changes in the ground contour and/or engagement with an obstruction.Steps 1312, 1314, 1316, 1318.

The wing blade 1119 may move upward automatically based on presence ofan upward force greater than a bias force provided by the compressiblegas. The upward force may be provided by a trip condition, such as aforce provided in response to the wing blade 1119 encountering anobject. Alternatively, the upward force may be provided by a change incontour of the ground that is not seen by the primary plow 1120 (e.g.,the ground contacting plane 1125 of the primary plow 1120 issubstantially unchanged, but the ground near the sliding portion 1121 ofthe wing blade 1119 is rising). Step 1312.

If the force encountered by the wing blade 1119 does not overcome thebias force, the wing blade 1119 may remain substantially stationary. Thebias force may vary as a function of the position of the wing blade1119. Because the gas in the actuator 1145 is compressible, the biasforce provided by gas may increase as the gas pressure rises in responseto upward displacement of the rod of the actuator 1145. If the wingblade 1119 has encountered a force exceeding the bias force, the controlsystem may provide hydraulic fluid to the rod side 1148 of the actuator1145 and the pressure of the compressible gas may increase. Step 1314.As a result, the rod may retract and therefore move the sliding portion1121 of the wing blade 1119 upward. In the illustrated embodiment, thesliding portion 1121 of the wing blade 1119 can move no farther upwardthan position H, which may be set by a physical configuration of thefirst wing 1110 (e.g., a stop or the actuator 1145). In one embodiment,the sliding portion 1121 may not move to position H in response to theupward force, and instead may move toward position H but not all the wayto position H because the upward force may balance with the increasingbias force (due to compression of the gas) prior to the wing blade 1119reaching position H.

Depending on the magnitude of upward force, the sliding portion 1121(and consequently the wing blade 1119) may move to any position betweenposition L and position H. If the upward force is removed or reduced,the sliding portion 1121 may move toward position A (between L and H),and hydraulic fluid on the rod side 1148 may be returned from theactuator 1145 to the hydraulic system. Step 1318. As mentioned herein,position A may correspond to a ground contact position, or position Amay be above the ground such that there is a space between the wingblade 1119 and the ground.

If the wing blade 1119 has not encountered an upward force thatovercomes the bias force, and the control system has received a signalfrom an operator to request to move the snow plow 1000 upward, thecontrol system may direct the wing blade 1119 and the snow plow 1000 tomove upward. If the control system has not received a signal requestingthe wing blade 1119 move upward or downward, the control system maycontinue to maintain the actuator 1145 at position A, waiting for eitheran upward force that exceeds the bias force or an operator providing asignal to move the wing blade 1119.

If the control system has received a signal from an operator requestingto move the snow plow 1000, the control system may determine if thesignal pertains to an upward movement request. Step 1320. If theoperator has requested upward movement, the hydraulic system may pushhydraulic fluid to the rod side of the lift actuator 1416. Step 1322. Inone embodiment, in response to additional hydraulic fluid on the rodside of the lift actuator 1416 and the actuator 1145, the pressure ofthe compressible gas may increase, while the rod retracts and the wingblade 1119 moves upward toward position H. After the actuator 1145 canretract no further, the pressure on the rod side of the lift actuator1416 may cause the lift actuator 1416 to retract.

In the embodiment depicted in FIG. 10 , an actuator 1114 is provided tooperably rotate the first wing 1110 about the first axis 1101 betweenthe F and B positions noted in conjunction with FIG. 2 . The actuator1114 may be a hydraulic actuator with its rod coupled to a bracket 1134and its cylinder coupled to the back of a mold board 1124 of the primaryplow 1120. As the rod retracts and extends, the rod actuates the bracket1134 to rotate the first wing 1110 about the axis 1101. In theillustrated embodiment, the actuator 1114 may have hydraulic fluid onboth the rod side and the cap side of the cylinder. Alternatively, thecap side of the actuator 1114 may include compressible gas operable tobias the actuator 1114 toward an extended position, but operable toallow the first wing 1110 to move toward position B in response toencountering a force that overcomes the bias force of the actuator 1114(e.g., encountering an obstruction). Alternatively, the rod side of theactuator 1114 may include a compressible gas operable to bias theactuator 1114 toward the retracted position B, and hydraulic fluid maybe supplied or removed from the cap side to position the actuator 1114at position F or between position F and B, compressing the gas on therod side of the actuator 1114. In this configuration, if the first wing1110 encounters an obstruction as the vehicle is being backed up (e.g.,backing up while the first wing 1110 encounters a light post), theactuator 1114 may automatically extend and allow the first wing torotate toward position F.

It is to be understood that any of the actuators described herein withcompressible gas may be positioned in this manner by supplying orremoving hydraulic fluid on the side opposite of the compressible gas,or allowed to float such that the compressible gas biases the actuatorto a mechanical limit of the actuator and/or the plow portion coupled tothe actuator.

An operator may use the control system to rotate the first wing 1110 inaccordance with the operator's directive in operation. When the controlsystem adds hydraulic fluid to the cap side of the actuator 1114 andremoves hydraulic fluid from the rod side of the actuator 1114, the rodextends and the first wing 1110 rotates about the axis 1101 away fromthe vehicle 10 to the requested position up to position F. When thecontrol system adds hydraulic fluid to the rod side of the actuator 1114and removes hydraulic fluid from the cap side of the actuator 1114, therod retracts and the first wing 1110 rotates around the axis 1101 towardthe vehicle 10 to the requested position up to position B. The extent towhich the first wing 1110 can rotate in either direction around the axis1101 may depend on the application. The second wing 1210 rotates in asimilar manner but may have a different range of rotation than the firstwing 1110, e.g., position F for the second wing 1210 may not correspondto position F for the first wing 1110.

In an alternative embodiment, the actuator 1114 may be operable to allowthe first wing 1110 to pivot toward the vehicle 10 up to position B inresponse to the snow plow 1000 encountering an object that exerts aforce greater than a tripping threshold or bias threshold. For example,the actuator 1114 may be configured to retract the rod in response to aforce that is applied on the first wing 1110 in a direction normal orperpendicular to the first axis 1101 and that is greater than thetripping threshold. In this way, the first wing 1110 may be configuredto yield in response to encountering an obstruction thus potentiallylimiting damage to the first wing 1110 and the snow plow 1000. While theactuator 1114 is used in this example, it is to be understood that anytype of tripping mechanism may be implemented in conjunction with thefirst wing 1110 to facilitate yielding in response to encounteringsignificant obstructions, including compressed gas on one-side of theactuator 1114.

In FIG. 12 , another view of the rear of the snow plow 1000 of FIG. 9 isshown. FIG. 12 focuses on the primary plow 1120. In the illustratedembodiment, two actuators 1330 are shown and are connected to the rearof the primary plow 1120 on the rod side and at an angle. On thecylinder side, the actuators 1330 are attached to a plow interface 1340,about which the primary plow 1120 may pivot. The plow interface 1340 issecured to the rear of the primary plow 1120 in a pivotable manner, suchthat the primary plow may pivot about a longitudinal axis 1103 parallelto a forward face of the primary plow 1120 (e.g., parallel to the moldboard 1124). The actuators 1330 may extend and retract to rotate theprimary plow 1120 about this longitudinal axis 1103. The actuators 1330may be coupled to the mold board 1124, as depicted in the illustratedembodiment, and can be secured to the primary plow 1120 by any suitablemeans, including removable pins.

In the illustrated embodiment, the actuators 1330 are hydraulicactuators with compressible gas on the rod side of the actuator 1330 andhydraulic fluid on the cap side of the actuator 1330 such that the rodis retracted and biased inward by the compressible gas on the cap side.The rod side of the actuator 1330 may include an accumulator, integralor external to the actuator 1330, filled with the compressible gas. Theactuators 1330 may be operable in a manner similar to the actuator 1145,with the exception of the actuator 1330 being configured to extendinstead of retract in response to a threshold force whereas the actuator1145 may be retracted in response to a threshold force. For example,with the snow plow 1000 in the down position with the hydraulic fluid infloat mode for the rod side of the lift actuator 1416, force applied tothe bottom of the mold board 1124 may apply longitudinal force on theactuator 1330 to compress the compressible gas in the actuator 1330 andcause the actuator 1330 to extend until a mechanical limit is reached.In response to the blade 1126 encountering an obstruction, the actuator1330 may extend compressing the gas.

If the primary plow 1120 encounters a tripping force (e.g., in responseto the main blade 1126 of the primary plow 1120 encountering anobstruction), the compressible gas may operate in a spring-like manner,allowing the actuators 1330 to extend as the gas further compresses. Ifthe actuators 1330 are coupled to external accumulators, gas in the rodside and the accumulator may compress and hydraulic fluid may floatsupplied to the cap side of the actuator 1330 such that the rod extends.As the rod extends, the primary plow 1120 rotates about a longitudinalaxis 1103 such that a blade 1126 of the primary plow 1120 moves towardthe vehicle 10 while the upper edge of the primary plow 1120 moves awayfrom the vehicle 10. If the tripping force occurred because the primaryplow 1120 encountered an obstruction, this tripping behavior may reduceor minimize damage to the primary plow 1120 and the snow plow 1000.After the tripping force is no longer present, the compressible gasexpands in the rod side of the actuator 1130 and at least a portion ofthe hydraulic fluid on the cap side of the actuator 1130 may be returnedto the hydraulic system, such that the rod of the actuator 1130retracts.

The actuators 1330 can also be controlled by the control system in amanner similar to method 1300, with the exception of the actuators 1330being biased toward a retracted position and the forces and positionspertaining to the position of the actuators 1330 instead of the actuator1145. In one embodiment, an operator can direct the control system toextend or retract the actuators 1330 to rotate the primary plow 1120respectively forward or back about the longitudinal axis 1103. To rotatethe primary plow 1120 forward, the control system may provide hydraulicfluid to the cap side of the actuators 1330 (via supply of fluid to thefluidly coupled rod side of the lift actuator 1416) further compressingthe compressible gas as the rod extends (optionally extending to itsmaximum length).

In one embodiment, the actuators 1330 (or any actuator described herein)may be replaced with a coupler configured similar to the actuator 1145.The coupler in this configuration may include compressible gas on arod-side or a cap-side that biases the coupler respectively to aretracted position or an extended position. Extension or retraction maybe mechanically limited by the coupler itself (e.g., full extension orretraction) or by a mechanical stop provided by the snow plow 1000. Thecoupler may extend or retract in a direction opposite the biasdirection, thereby compressing the gas provided in the coupler. Thisextension or retraction may allow the snow plow 1000 to move in responseto an applied force greater than the bias force provided by thecompressed gas in the coupler. As an example, in the case of theactuator 1330 being provided with compressible gas on a rod side of theactuator 1330, the coupler may be biased toward a retracted position bycompressible gas. In response to the blade 1126 of the snow plow 1000encountering an obstruction, the coupler may extend (compressing the gasfurther) and allow the snow plow 1000 to yield or move in response tothe obstruction. After the obstruction or an applied force is no longerpresent, the coupler may retract to the bias position. This type ofcoupler may be used in place of conventional springs provided to allow aconventional plow to tilt forward in response to the plow hitting anobstruction. It is further noted that a coupler having compressible gasin accordance with one embodiment may avoid multiple of suchconventional springs, with a more compact configuration and may furtherbe adjustable by changing the pressure of the compressible gas. It isfurther noted that the coupler in one embodiment of the presentdisclosure, in contrast to a conventional extendable springconfiguration for a plow, can be configured with a bias force forextension or retraction.

In the illustrated embodiments, one or more actuators (or a coupler) mayinclude compressible gas (internal and/or external). The compressiblegas may be provided to an actuator via a valve 1133, 1137 (e.g., aSchrader valve). The pressure of the compressible gas in an actuator canbe varied via the valve, allowing adjustment of a bias force of theactuator.

In the illustrated embodiment of FIG. 12 , the snow plow 1000 is coupledto a vehicle support 1412 in a pivotal manner relative to first andsecond vehicle couplings 1414. The vehicle support 1412 may be removablycoupled to the frame of the vehicle 10, in accordance with one or moreembodiments described herein, including the configuration described inconnection with the snow plow 2000. The plow support 1380 may be raisedand lowered relative to the vehicle support 1412 by a lift actuator1416, which is coupled to the plow support 1380 via lift coupling 1418.For instance, the lift actuator 1416 may be extended to lower the snowplow 1000 into contact with the ground, and the lift actuator 1416 maybe retracted to raise the snow plow 1000 for transportation. Asdescribed herein, first and second actuators 1370 may extend and retractto move the snow plow 1000 proximal to and distal from the vehicle 10.In a transport mode, the first and second actuators 1370 may retract thesnow plow 1000, the lift actuator 1416 may raise the snow plow 1000, andthe actuator 1114 may move the wings to the B position, such that thesnow plow 1000 is close to the vehicle, clears the ground, and fitswithin lane constraints of the road.

The first and second vehicle couplings 1414 and a coupling of the liftactuator 1416 opposite the lift coupling 1418 may be disconnected by anoperator to remove the plow support 1380 and the snow plow 1000 from thevehicle support 1412. Alternatively, the snow plow 1000 may be removedfrom the vehicle 10 via a vehicle support 1412 configured similar to thevehicle support 2412 described herein, and operated to disconnect from avehicle mount 112.

The snow plow 1000 is described herein in conjunction with one or moreactuators or couplers having compressible gas to bias the actuator orcoupler toward a retracted or extended position and to allow extensionor retraction in response to an applied force. It is to be understoodthat the snow plow 1000 is not so limited. An external spring orspring-like component may be provided in conjunction with one or moreactuators or couplers to bias toward a retracted or extended positionand facilitate extension or retraction in response to an applied force.For instance, a compressible spring may be provided in conjunction withthe actuator 1370 to bias the actuator 1370 and the plow toward the Oposition. In response to the plow encountering an obstruction or a forceapplied toward position I, the compressible spring may enable the plowand the actuator 1370 to retract.

In the illustrated embodiments of FIGS. 12 and 14 , the snow plow 1000and the blade 1126 may be lifted off the ground by retraction of thelift actuator 1416. The angle of the snow plow 1000 relative to thelongitudinal axis 1103 may be varied by the actuators 1330. With thisarrangement, the forward position and height of the snow plow 1000 andblade 1126 can be controlled while also maintaining an angle of the snowplow 1000 relative to the longitudinal axis 1103. In the illustratedembodiment, in response to lifting the snow plow 1000 to a raisedposition, the actuators 1330 may extend due to pressure in the hydraulicsystem and tilt the snow plow forward in a raised position.

In an alternative embodiment, the angle of the snow plow 1000 may becontrolled separately from the position of the lift actuator 1416. Forinstance, the angle of the snow plow 1000 may be kept in a generallyvertical manner by extending or retracting the actuators 1330 based onthe forward position and height of the snow plow 1000 determined by thelift actuator 1416 and the first and second actuators 1370.

By controlling the angle of the snow plow 1000 in conjunction with theheight and forward position, the snow plow 1000 can be maneuvered tocomply with road width limitations, avoid contact between the wings1112, 1212 and the ground (particularly the tips of the wings 1112, 1212as depicted in FIG. 14 ). Additionally, the snow plow 1000 can betransitioned among various modes of operation, including a plow modewith the snow plow 1000 in contact with the ground, a stacking mode inwhich the snow plow 1000 is raised for pushing and stacking snow abovethe ground, and a transportation mode in which the snow plow 1000 isstowed for travel. In these various modes, despite changes in height andforward position of the snow plow 1000 relative to the vehicle, theangle of the snow plow 1000 may be adapted to be generally vertical (oranother angle in accordance with operator directive).

To rotate the primary plow 1120 backward, the control system may removehydraulic fluid or remove pressure from the cap side of the actuator1330 so that the compressible gas can further retract the rod. Dependingon the height of the primary plow 1120 and the first and second wings1112, 1212, and the position of the first or second wings 1112, 1212relative to the B and F positions, the primary plow 1120 may be limitedin rotating backward around the longitudinal axis 1103 because the firstwing 1110 and the second wing 1210 may come into contact with theground. Contact in this manner may cause wear or damage to the wingblades 1119, 1219. The angle of the primary plow 1120 and/or the heightof the wing blades 1119, 1219 may be adjusted as the height of theprimary plow 1120 is varied by retraction of the lift actuator 1416, asshown for example in the transition to the plow mode depicted in FIG. 14. The positions of the actuators shown in FIG. 14 for the various modesof operation may or may not correspond to the maximum retraction orextension of the actuators, depending on the application.

The position of the snow plow 1000 may be obstructed from the driver'sview by portions of the vehicle 10. For instance, from his or herposition in the cabin of the vehicle 10, the driver may be unable to seethe position of the snow plow 1000 over the hood of the vehicle 10. Tofacilitate visibility, the snow plow 1000 may include one or morevisibility markers 1020. The visibility markers 1020 may be attached tothe outer edges of the primary plow 1120, the first wing 1110, and thesecond wing 1210. The visibility markers 1020 allow a driver of thevehicle 10 to more easily see the position of the snow plow 1000.

In the illustrated embodiment, the vehicle support 1412 may be removablycoupled to the frame of a vehicle 10, via a vehicle mount 112. The snowplow 1000 may be releasably coupled to the vehicle 10 via couplingbetween the vehicle support 1412 and the vehicle mount 112. The snowplow 1000 can be retrofitted for a range of mounting configurations forthe vehicle 10 and is not limited to the vehicle support 1412.

In one embodiment, the plow support 1380 of the snow plow 1000 comprisesa receiver 1350, which may be configured to support a receiver interface1360. The plow support 1380 may removably attach to the vehicle support1412. The receiver 1350 of the plow support 1380 and the receiverinterface 1360 may allow the snow plow 1000 to move proximally anddistally relative to the vehicle 10. As shown in FIG. 13 , the receiver1350 is coupled to the plow support 1380, and the plow support 1380 isattached to the vehicle support 1412. Alternatively, the receiver 1350may be coupled directly to the vehicle support 1412. In the depictedembodiment, the receiver 1350 defines an opening configured to receive areceiver interface 1360 and the receiver interface 1360 is movablycoupled to the receiver 1350. For example, the receiver interface 1360may be a protrusion or a shank. As depicted, the receiver interface 1360forms part of the plow interface 1340 and extends from the rear surfaceof the primary plow 1120. In an alternative embodiment, the receiverinterface 1360 may be a separate component from the plow interface 1340and may not be coupled to the plow interface 1340. In anotheralternative embodiment, the receiver interface 1360 may be a separatecomponent from the plow interface 1340 but may be coupled to the plowinterface 1340. In one embodiment, the receiver 1350 and the receiverinterface 1360 are operable to restrict movement in directionsperpendicular to a longitudinal axis of the receiver 1350 such thatmovement is substantially prevented in directions perpendicular to thelongitudinal axis.

The receiver 1350 may be coupled to at least one actuator 1370 via theplow interface 1340. The actuators 1370 may be coupled to the plowsupport 1380 on the cylinder side and to the plow interface 1340 on therod side. In an alternative embodiment, the actuators 1370 may bedirectly coupled to the receiver 1350 on the cylinder side, directlycoupled to the mold board 1124 on the rod side, or both. As depicted,the actuators 1370 are hydraulic actuators with hydraulic fluid on boththe rod side and compressed gas on the cap side of the cylinder. Theactuators 1370 may be biased in the extended position via compressed gason the cylinder side of the actuators 1370, and operative to retract inresponse to a force greater than the bias force of the actuators 1370(e.g., in response to the snow plow 1000 encountering an obstruction.)The actuators 1370 may be controlled by providing hydraulic fluid underpressure to the rod side of the actuators 1370 to retract the actuators1370. If pressure is removed from the rod side of the actuators 1370,the actuators 1370 may extend until mechanically limited based onexpansion of the compressible gas.

In an alternative embodiment, the receiver 1350 may attach to theprimary plow 1120 and the receiver interface 1360 may attach to the plowsupport 1380. The actuator 1370 may be mounted with the rod sideattached to the plow interface 1340 (as shown) or the plow support 1380.

An operator can control the distance between the snow plow 1000 and thevehicle 10 by directing the control system to move the snow plow 1000between position O and position I. In response to receiving a commandfrom an operator to move the snow plow 1000 toward position I, thecontrol system may supply hydraulic fluid to the rod side of theactuator 1370, further compressing compressible gas on the cylinder sideof the actuator 1370. In the illustrated embodiment, the actuators 1370include external accumulators 1371 coupled to the cylinder side andcapable of storing compressible gas in conjunction with the cylinderside of the actuators 1370. The external accumulator 1371 may facilitategreater length of travel for the actuator 1370 relative to aconfiguration without the external accumulator 1371, providing gas ofsufficient pressure throughout the range of motion of the actuator 1370and sufficient bias force to retract in response to an obstruction butnot in response to pushing snow or debris. In an alternative embodiment,the actuators 1370 may not include compressible gas on the cylinderside, and may be actuated by hydraulic fluid in a push-pull coordinatedmanner on the cylinder side and rod side.

Movement toward position I causes the receiver interface 1360 to slidefurther into the receiver 1350. Position I is the closest the snow plow1000 can be moved to the vehicle 10 proximally, and may vary fromapplication to application depending on the construction. Position I maybe the position of the snow plow 1000 when the rods of the actuators1370 are fully retracted.

Alternatively, or additionally, position I may be the position of thesnow plow 1000 when the receiver interface 1360 is fully seated in thereceiver 1350. In another embodiment, position I may be the position ofthe snow plow 1000 when the receiver interface 1360 contacts a back edgeof the receiver 1350, which may or may not be the point at which thereceiver interface 1360 is fully covered by the receiver 1350.

If the control system receives a command from an operator to move thesnow plow 1000 toward position O, the control system may withdrawhydraulic fluid to the rod side of the actuator 1370. This causes therods to extend and the receiver interface 1360 to slide out of thereceiver 1350. Position O may correspond to the farthest the snow plow1000 can be disposed from the vehicle 10 distally. In one embodiment,position O is reached when the rods of the actuators 1370 are fullyextended. In one embodiment, the rods are 14″ long. Additionally, oralternatively, position O may be the position of the snow plow 1000 whenthe end of the receiver interface 1360 reaches the end of the receiver1350. In one embodiment, position O is selected to substantially preventoverextension of the actuators 1330. For example, if the cylinder sideof the actuators 1330 is coupled to the plow support 1380 rather thanthe plow interface 1340, position O may be selected to be more proximalto the vehicle 10 in order to prevent overextension of the actuators1330.

As described herein, the actuators 1370 may have compressible gas on thecap side of the cylinder and hydraulic fluid on the rod side of thecylinder such that the rod is biased in the extended position. Thus, theprimary plow 1120 is biased at position O. When the primary plow 1120comes into contact with a force above a tripping threshold or overcomesa bias force of the actuators 1370, the actuators 1370 may operate in aspring-like manner, and hydraulic fluid is provided to the rod side ofthe cylinder and the compressible gas compresses further in the cylinderside and the external accumulator 1371 such that the rod of eachactuator 1370 retracts and moves the primary plow toward position I. Theprimary plow 1120 may move all the way to position I or may move to someposition between position O and position I depending on the strength ofthe obstruction force. This allows the primary plow 1120 to yield whenencountering an obstruction which may prevent or reduce damage to thesnow plow 1000. When the obstruction force is no longer present,hydraulic fluid may be withdrawn from the rod side of the actuator 1370(e.g., automatically in response to pressure from the gas) and thecompressible gas may expand such that the actuators 1370 are once againbiased toward the extended position and the primary plow 1120 returns toposition O or a position between 0 and I at which the operator hasselected for operation.

If the vehicle 10 with the snow plow 1000 is travelling from place toplace, it can be configured in a transport mode as depicted in theillustrated embodiment of FIG. 14 . The snow plow 1000 can be in avariety of positions during transport mode. For example, the primaryplow 1120 may be tilted forward about the longitudinal axis 1103 and thefirst wing 1110 and the second wing 1210 may be rotated around the axes1101, 1201 back toward the vehicle 10. This lifts the blade 1126 off theground and keeps it behind the primary plow 1120 while driving such thatthe blade 1126 is not the first point of contact if the snow plow 1000comes into contact with an obstruction. The control system may move thesnow plow 1000 to this position by adjusting the length of the liftactuator 1416, the actuators 1330, the actuators 1370, and the actuators1114, 1214. To tilt the primary plow 1120 forward, the control systemsupplies hydraulic fluid to the cap side of the actuators 1330 furthercompressing the compressible gas. This causes the rods of the actuators1330 to extend, pushing the top edge of the primary plow 1120 forwardand consequently tilting the blade 1126 toward the vehicle 10. To movethe first wing 1110 and the second wing 1210 backwards, the controlsystem removes hydraulic fluid from the cap side of the actuators 1114,1214 and supplies hydraulic fluid to the rod side of the cylinders ofthe actuators 1114, 1214, which causes the rods to retract. As the rodsretract, the first wing 1110 is rotated about the axis 1101 toward thevehicle 10 and the second wing 1210 is rotated about the axis 1201toward the vehicle 10. As the primary plow 1120 tilts forward, the outeredge of the first wing 1110 and the second wing 1210 and the wing blades1119, 1219 lift off the ground and rotate toward the vehicle 10. Thismay provide a safer transport mode because all blades are rotated backtoward the vehicle 10.

There are applications where controlling the distance of the snow plow1000 relative to the vehicle 10 is useful. For example, when parking thevehicle 10, an operator may want to move the snow plow 1000 closer tothe vehicle 10 in order to allow the vehicle 10 to better fit into aparking space. An operator may want the snow plow 1000 to be furtheraway from the vehicle 10 when plowing in order to minimize blowback ofthe snow onto the vehicle 10 or to provide less clearance between thesnow plow 1000 and the vehicle 10 when the snow plow 1000 is actuated toits transport mode. The closer the snow plow 1000 is to the vehicle 10during transport, the closer the center of gravity of the vehicle 10 andthe snow plow 1000 is to the vehicle's center of gravity without thesnow plow 1000, and the more even the weight of the system isdistributed over the wheels.

Although a moveable portion (e.g., a wing blade 1119) is described inconjunction with a wing 1110 relative to a primary plow 1120, it is tobe understood that the present disclosure is not so limited. The snowplow 1000 may include any number of segments, such as two segments thatform the primary plow 1120 capable of forming a V-configuration (e.g., aV plow). As another example, the snow plow 1000 may include foursegments, including two segments that form a V-configuration and twowings respectively coupled to one of the two segments that form theV-configuration. Any segment of the snow plow 1000 may include a movableportion configured according to one or more embodiments describedherein. For instance, a V-plow may include wing blades 1119 capable ofrotating upward and downward relative to a pivot point to follow theground contour and/or move in response to encountering an obstruction.In another example, with a four segment plow, each segment may include arotatable or movable portion capable of following the ground.

II. Alternative Front Plow

Another alternative embodiment a snow plow in the form of a front-bladeplow is shown in FIGS. 14-22 and generally designated 2000. Thefront-blade plow is similar to the snow plow 1000 described herein withseveral exceptions. For instance, the snow plow 2000 may be mounted tothe front of the vehicle 10 as depicted in FIG. 14 , and may be coupledto a vehicle support 2412 via a plow support 2380. The vehicle support2412 may be removably coupled to a vehicle mount 112, which is attachedto the vehicle 10. In other words, the snow plow 2000 may be mounted tothe front of the vehicle 10 via the vehicle supports 2412 and thevehicle mounts 112.

It is noted that the snow plow 2000 in the illustrated embodimentincludes many components configured in a manner similar to components ofthe snow plow 1000, with several exceptions as described herein. Forpurposes of disclosure, components of the snow plow 2000 are designatedwith a 2000 series reference number, and similar components of the snowplow 1000 are designated with a 1000 series reference number.

The vehicle mount 112, in the illustrated embodiment of FIGS. 14-20 , isattached to a frame of the vehicle 10. The vehicle mount 112 may beinstalled at the time of manufacture or by a third party in a retrofitof the vehicle 10.

The vehicle mount 112 in the illustrated embodiment may include a guideslot 114 operable to receive and guide a lower pin 2415 to a lowerreceiver 116, which may be in the form of a hook operable to support andmaintain a position of the lower pin 2415. The vehicle mount 112 mayinclude an upper receiver 118 operable to receive a moveable upper pin2419, which can be moved via a handle 2421, which is depicted in theillustrated embodiment of FIG. 18 , and which is spring loaded to returnthe upper pin 2419 into the upper receiver 118 if present.

As described herein, the vehicle support 2412 along with the snow plow2000 may be removably coupled to the vehicle mount 112. For purposes ofdisclosure, a sequence of steps for decoupling the vehicle support 2412from the vehicle mount 112 is described with respect to FIGS. 18-20 .Coupling the vehicle support 2412 to the vehicle mount 112 may beconducted in the reverse.

Starting with FIG. 18 , a coupling block B may be provided beneath theplow support 2380. The handle 2421 may be operated to remove the upperpin 2419 from the upper receiver 118, enabling removal of the lower pin2415 from the lower receiver 116. After the upper pin 2419 has beenremoved from the upper receiver 118, the lift actuator 2460 may becontracted to rotate the vehicle support 2412 via rotatable coupling2414 between the vehicle support 2412 and the plow support 2380. Withthe plow support 2380 being supported by the coupling block B, and withthe upper pin 2419 removed from the upper receiver 118, retraction ofthe lift actuator 2460 may cause the lower pin 2415 to disengage fromthe lower receiver 116 of the vehicle support 112. The guide slot 114may guide the lower pin 2415 in disengaging from the lower receiver 116and ultimately from the vehicle supports 112, as shown in theillustrated embodiment of FIG. 20 .

As seen in the illustrated embodiment of FIG. 18 , the vehicle support2412 may include a receiver plate 2423 spaced apart from a main body2425 of the vehicle support 2412 to define a gap therebetween that isoperable to receive the upper receiver 118 and the lower receiver 116 ofthe vehicle mounts 112. The ends of the main body 2425 and the receiverplates 2423 that are proximal to the vehicle 10 may be angled away fromthe upper receiver 118 and the lower receiver 116, facilitating andguiding receipt of the upper receiver 118 and lower receiver 116 betweenthe main body 2425 and the receiver plates 2423 as the vehicle mount 112and the vehicle supports 2412 are moved into proximity to each other forcoupling therebetween.

As described herein, the snow plow 2000 is similar to the snow plow 1000in many respects. For instance, the snow plow 2000 may include a primaryplow 2120 coupled to the plow support 2380, similar respectively to theprimary plow 1120 and the plow support 1380. The snow plow 2000 may alsoinclude a first wing 2110 that may be rotatably coupled to the primaryplow 2120 on a first side 2122 via a joint 2117. The first wing 2110,the first side 2122, and the joint 2117 may also be similar respectivelyto the first wing 1110, the first side 1122, and the joint 1117. Thejoints 2117 may allow the first wing 2110 to rotate about an axis 2101to a position F and a position B. Positions F and B may vary dependingon the application, as described herein, and rotation about the axis2101 may allow the first wing 2110 to rotate toward the vehicle toposition B and to rotate away from the vehicle 10 to position F. Thesecond wing 2210 may be similar to the first wing 2110, with componentssimilar to the 2100 series reference numbers being designated with a2200 series reference number.

The first wing 2110 may include a main wing portion 2112 and a wingblade 2119. The wing blade 2119 may be fixedly connected to the mainwing portion 2112, or the wing blade 2119 may be able to rotate upwards,for example in response to a change in contour of the ground orencountering debris or an obstruction that exerts a force greater than atripping threshold.

In one embodiment, the wing blade 2119 may include a pivot portion 2118and a sliding portion 2121. In the depicted embodiment, the slidingportion 2121 includes a fastener seated within or captured by a channelor slot to allow the wing blade 2119 to move upward in response to anupward force (e.g., a tripping force or the ground in response to achange in surface contour), while maintaining a coupling between thesliding portion 2121 and the main wing portion 2112. The wing blade 2119may rotate about the pivot portion 2118 such that the sliding portion2121 moves from position L to position H. The position L may correspondto a position lower than a ground contacting plane 2125 defined by theblade 2126 of the primary plow 2120, and position H may correspond to aposition higher than this ground contacting plane 2125 defined by thewing blade 2119.

In use, the position of the sliding portion 2121 of the wing blade 2119may be between position L and H with the wing blade 2119 contacting theground. The position of the sliding portion 2121 may vary as the contourof the ground changes. As described herein, the sliding portion 2121 ofthe wing blade 2119 may be biased toward the ground such that, as theplow 2000 travels along the ground and the ground contour lowersrelative to a current position of the sliding portion 2121, the slidingportion 2121 may lower toward position L to allow the wing blade 2119 tofollow the contour of the ground. Conversely, the sliding portion 2121may rise toward position H as the ground contour rises with the plowtravelling over the ground and the height of the ground near the slidingportion 2121 being different from the height of the ground near thepivot portion 2118. The bias force may vary from application toapplication, and may be determined selectable, in operation,installation, or the design stage, or a combination thereof, to enablethe sliding portion 2121 of the wing blade 2119 to substantiallymaintain contact of the wing blade 2119 with the ground and to allowupward movement in response to changes in ground contour and/or anencounter with an obstruction.

In the illustrated embodiment of FIG. 16 , another view of the rear ofthe snow plow 2000 is shown. FIG. 12 focuses on the primary plow 2120,and depicts two actuators 2330 connected to the rear of the primary plow2120. On the rod side of the actuators 2330 and at an angle, theactuators 2330 are coupled to the primary plow 2120 in a pivotal manner.On the cylinder side of the actuators 2330, the actuators 2330 areattached to a plow interface 2340, about which the primary plow 2120 maypivot. It is to be understood that the actuators 2330 may be coupled tothe primary plow 2120 and the plow interface 2340 in a different manner,such as, for example, with the rod side of the actuators 2330 coupled tothe plow interface 2340.

The plow interface 2340, in the illustrated embodiment, is secured tothe rear of the primary plow 2120 in a pivotable manner, such that theprimary plow may pivot about a longitudinal axis 2103 parallel to aforward face of the primary plow 2120 (e.g., parallel to the mold board2124). The actuators 2330 may extend and retract to rotate the primaryplow 2120 about this longitudinal axis 2103. The actuators 2330 may becoupled to the mold board 2124, as depicted in the illustratedembodiment, and can be secured to the primary plow 2120 by any suitablemeans, including removable pins.

In the illustrated embodiment, the actuators 2330 are hydraulicactuators, similar to the actuators 1330, with compressible gas on therod side of the actuator 2330 and hydraulic fluid on the cap side of theactuator 2330 such that the rod is retracted and biased inward by thecompressible gas on the rod side, e.g., with the hydraulic fluid on thecap side being in a float state. The rod side of the actuator 2330 mayinclude an accumulator 2331, integral or external to the actuator 2130,filled with the compressible gas. The actuators 2330 may be operable ina manner similar to the actuator 2145, with the exception of theactuator 2330 being configured to extend instead of retract in responseto application of a threshold force. It is noted that the hydraulicsystem, as described herein, may be transitioned from a float state toan active state that involves one or more of retracting the liftactuator 2416, extending the actuators 2330, retracting the actuators2145 operable to raise and lower the wing blades 2119, and retractingthe actuators 2370. Transitioning back to a float state may allow thecompressible gas to do the reverse, including one or more of extendingthe lift actuator 2416, retracting the actuators 2330, extending theactuators 2145 operable to raise and lower the wing blades 2119, andextending the actuators 2370. The compressible gas associated with eachof these actuators may bias portions of the snow plow 2000 toward one ormore biased positions, which can be overcome by application of forcesuch as contact with the ground or an obstruction.

In one embodiment, one or more actuators may be operable to controlmovement of different parts of the snow plow 2000, including differenttypes of components in different movements (such as the lift actuator2145, actuators 2330, actuators 2370, and the actuators 2145). Such oneor more actuators may operate in conjunction with each other to providefreedom of movement for the snow plow 2000 in multiple directions forcomponents of the snow plow 2000 in response to encountering anobstruction. In other words, different longitudinal axes may be providedfor a plurality of actuators that move in response to encountering anobstruction. For example, in response to the mold board 2124 of the snowplow 2000 encountering an obstruction, the lift actuator 2416 mayretract, the actuators 2330 may extend, and the actuators 2370 mayretract. This movement of the lift actuator 2416, the actuators 2330,and the actuators 2370 may be enabled via compression of gas provided inthe respective actuators. In this way, multiple components of the snowplow 2000 may yield or move in response to a portion of the snow plow2000 encountering an obstruction.

In another example, if the primary plow 2120 encounters a tripping force(e.g., in response to the main blade 2126 of the primary plow 2120encountering an obstruction), the compressible gas may operate in aspring-like manner, allowing the actuators 2330 to extend as the gasfurther compresses. If the actuators 2330 are coupled to externalaccumulators, gas in the rod side and the accumulator may compresswithin the external accumulator and hydraulic fluid may be supplied tothe cap side of the actuator 2330 as the rod extends. As the rodextends, the primary plow 2120 may rotate about the longitudinal axis1103 such that the blade 2126 of the primary plow 2120 moves toward thevehicle 10 while the upper edge of the primary plow 2120 moves away fromthe vehicle 10. If the tripping force occurred because the primary plow1120 encountered an obstruction, this tripping behavior may reduce orminimize damage to the primary plow 2120 and the snow plow 2000.Although, in this example, the actuators 2330 are described as extendingin response to the snow plow 2000 encountering an obstruction force,additional or alternative actuators of the snow plow 2000 may extend orretract in response to the snow plow 2000 encountering an obstruction.For instance, in addition to extension of the actuators 2330, the liftactuator 2416 and/or the actuators 2370 may retract in response to thesnow plow 2000 encountering the obstruction.

In the illustrated embodiment, the snow plow 2000 may include ahydraulic system 2420, similar to the hydraulic system described hereinin conjunction with the snow plow 1000. The hydraulic system 2420 may behydraulically coupled to the actuators of the snow plow to controlmovement thereof. The hydraulic system 2420 may include a singlehydraulic coupling for each of the actuators of the snow plow 2000 (or asubset thereof), including the lift actuator 2416, the actuators 2330,the actuators 2370, and the actuators 2345. The single hydrauliccoupling may be operable to control supply of fluid to one side of theactuators, while the other side of the actuators may be filled withcompressible gas (which is optionally in gaseous communication with anaccumulator). In one embodiment, the actuators having a single hydrauliccoupling (e.g., the lift actuator 2416, the actuators 2330, theactuators 2370, and the actuators 2345) may be controlled together via ahydraulic valve operable to control supply of hydraulic fluid to all ofthese actuators simultaneously. In one embodiment, the single hydrauliccouplings may define branch circuits that are linked to a sourcehydraulic circuit, for which hydraulic fluid is controlled by thehydraulic valve. In other words, the hydraulic couplings for the one ormore of the lift actuator 2416, the actuators 2330, the actuators 2370,and the actuators 2345 may all form part of the same hydraulic circuit,for which hydraulic fluid is controlled by the hydraulic valve. Withthis configuration, hydraulic actuation of the lift actuator 2416, theactuators 2330, the actuators 2370, and the actuators 2345 may beconducted simultaneously, such as to transition the snow plow 2000 froman operable position to a transport position, at which the primary plow2120 is raised relative to the ground, the wing blades 2119, 2219 areraised to position H relative to the ground, and the primary plow 2120is tilted forward about the longitudinal axis 2103. In one embodiment,because the primary plow 2120 is tilted forward about the longitudinalaxis 2103 and the wing blades 2119, 2219 are raised to position H, thewings 2110, 2210 may be rotated to position B, via control by thehydraulic system 2420, in a manner that provides ground clearance fortravel and maintains a left to right width of the vehicle 10 that fitswithin a standard lane size of the road.

The actuators 2330 in the illustrated embodiment are respectivelycoupled to the rear of the primary plow 2120 via an upper mount and tothe plow interface 2340 via a lower mount. The upper mount may includefirst and second upper plates spaced apart to receive an upper endportion of the actuator 2330. The first upper plate may include aplurality of apertures that are respectively axially aligned with acorresponding plurality of apertures disposed in the second upper plate.The apertures may accept a pin or bolt that rotatably couples to anupper end portion of the actuator 2330 to the upper mount.

The apertures of the first and second upper plates may be spacedrelative to each other to enable coupling of the actuator 2330 to theupper mount at a plurality of positions. For example, the plurality ofpositions of the upper mount may enable coupling the upper end portionof the actuator 2330 at different positions, some closer to thelongitudinal axis 2103 and some farther from the longitudinal axis 2103.The lower mount for the actuators may be similar in some respects to theupper mount, including first and second lower plates spaced apart toreceive a lower end portion of the actuator 2330. The first and secondlower plates may each include a plurality of apertures that are axiallyaligned and provide for multiple coupling positions for the actuator2330. The plurality of apertures of the lower mount may enable couplingthe lower end portion of the actuator 2330 at different positions, somecloser to the longitudinal axis 2103 and some farther from thelongitudinal axis 2103.

In practice, it is noted that the mounting position of the actuator 2330relative to the plow interface 2340 and the primary plow 2120 may bevaried or adjusted to configure the snow plow 2000 for use with aparticular truck. For instance, a height of one vehicle 10 may bedifferent from the height of another vehicle 10. The mounting positionsof the actuators 2330 may be adjusted to set the angle of the primaryplow 2120 (and the angles of the first and second wings 2110, 2210)relative to the ground.

An upper end of the actuator 2330 may be mounted via a pin to one of aplurality of available positions provided by the upper mount, and thelower end of the actuator 2330 may be mounted via a pin to one of aplurality of available positions provided by the lower mount. Byselecting upper and lower mounting positions for the actuator 2330, aninstaller or maintenance worker can tune the snow plow 2000 to theground (e.g., an angle of the snow plow relative to the ground and thetruck), enabling different truck configurations without changing themounting iron (e.g., the vehicle mount 112 and/or vehicle support 2412)or construction thereof. For instance, the installer or maintenanceworker may select sets of holes from the upper and lower mounts for theactuator 2330 for setting both the length and angle of the actuator 2330relative to the primary plow 2120 and the plow interface 2340.

In one embodiment, a geometry of the snow plow 2000 relative to thetruck and the ground may vary over time (e.g., as one or more bladeswear). A maintenance worker may adjust the upper position or lowerposition, or both, of the actuator 2330 relative to the upper and lowermounts in order to re-adjust the position of the primary plow 2120 withrespect to the ground and the truck. For instance, the upper endportions of the actuators 2330 may be moved to sets of apertures thatare 2 inches farther from the longitudinal axis 2103, and the low endportions of the actuators 2330 may be moved to sets of apertures thatare 0.5 inches closer to the longitudinal axis.

In the illustrated embodiment, the angle of the primary plow 2120relative to the ground and truck may affect the angle of the axes 2101,2201 of the first and second wings 2110, 2210 relative to the ground.This angle may affect the available travel and pivot angle of the wingblades 2119, 2219 between positions H and L. As the main blade 2126wears, a portion of the wing blades 2119, 2219 proximal to the axes2101, 2201 may wear, potentially causing the distal portion 2131, 2231of the wing blades 2119, 2219 to rise toward position H despite lesswear than the portion of the wing blades 2119, 2219 proximal to the axes2101, 2201. This movement toward position H may limit the amount ofupward travel of the wing blades 2119, 2219 that is available inresponse to encountering an obstruction.

To account for the effects of blade wear, including the limiting ofavailable movement toward position H for the wing blades 2119, 2219, themounting locations of the actuators 2330 may be adjusted to change theangle of the primary plow 2120 relative to the ground. For instance, themounting locations of the actuators 2330 may be adjusted to pivot anupper portion of the primary plow 2120 away from the vehicle 10, therebyangling the axes 2101, 2201 to provide a greater amount of travel fordistal portions 2131, 2231 of the wing blades 2119, 2219 betweenposition H and the ground (despite wear of the main blade 2126). Inother words, by adjusting the mounting locations of the actuators 2330and the angle of the axes 2101, 2201, despite wear of the main blade2126, an operating position of the wing blades 2119, 2219 may bere-adjusted to be similar to the operating position of the wing blades2119, 2219 prior to the blade wear and enabling a similar amount oftravel (e.g., 3 inches of upward motion) between the operating positionand position H in response to encountering an obstruction. In theillustrated embodiment, each of the actuators 2114 of the snow plow2000, in the illustrated embodiment, may be coupled to the hydraulicsystem 2420 via first and second hydraulic couplings, enabling thehydraulic system to actively control an angular position of each of thewings 2110, 2210 between the F and B positions.

The operation of the compressible gas and hydraulic system 2420 inconjunction with the snow plow 2000 is similar in many respects to theoperation of the compressible gas and hydraulic system of the snow plow1000. In one embodiment, the snow plow 2000 may be configured such thatthe lift actuator 2416, as depicted in the illustrated embodiment ofFIG. 16 , may be provided with compressible gas on one side of the liftactuator 2416. The compressible gas in the illustrated embodiment may beprovided on the cylinder side of the lift actuator 2416, optionally inconjunction with an accumulator 2417, and biasing the lift actuator 2416to an extended position if the hydraulic fluid on the rod side of thelift actuator 2416 is allowed to float or return to the tank. With thesnow plow 2000 positioned in an operable position, the bias of the liftactuator 2416 may provide downforce on the plow support 2380 to bias theprimary plow 2120 and the wings 2110, 2210 toward the ground. With theground contour changing as the snow plow 2000 is driven over the ground,the lift actuator 2416 may vary in length via compression of thecompressible gas on the cylinder side of the lift actuator 2416. Inother words, the changes in ground height may overcome the bias force ofthe lift actuator 2416 (or downforce of the lift actuator 2416),allowing the primary plow 2120 and the wings 2110, 2210 to follow thecontour of the ground.

In the illustrated embodiment, the accumulator 2417 is depicted as beingcoupled directly to the lift actuator 2416. It is to be understood thatthe accumulator 2417 may be separate from the lift actuator 2416, anddirectly fluidly coupled to the lift actuator 2416. It is also to beunderstood that the accumulator 2417 regardless of whether theaccumulator 2417 is mounted directly to or separate from the liftactuator 2416, the accumulator 2417 may be indirectly fluidly coupled tothe lift actuator 2416. For instance, the accumulator 2417 may beindirectly fluidly coupled to the lift actuator via a pneumatic valve2413 as described herein. In one embodiment, the accumulator 2417 may beintegrated with a structural component of the snow plow 2000 to form astructural integrated accumulator—e.g., the accumulator 2417 may beprovided by an internal space of a structural tubular member of the snowplow 2000. More specific to this example, the accumulator 2417 may beprovided by the cross member of the vehicle support 2412 to which theupper portion of the lift actuator 2416 is coupled. A Schrader valve maybe mounted to a flange that forms a seal with an internal cavity of thiscross member, which is depicted in the illustrated embodiment of FIG. 16. A gas line may also be coupled to the structural integratedaccumulator, where the gas line may be directly coupled to the liftactuator 2416 or indirectly via a pneumatic valve 2413. In the indirectconfiguration, another gas line may couple the pneumatic valve 2413directly to the lift actuator 2416.

A method of operation in accordance with one embodiment is shown in FIG.23 and generally designated 3000. As described herein, the lift actuator2416 may be operable to raise and lower the snow plow 2000, and themethod 3000 is described in conjunction with operation of the liftactuator 2416 by the hydraulic system 2420. The method 3000 is notlimited to operation with the lift actuator 2416. The method 3000 may beimplemented in conjunction with any type of actuator, including any oneor more of the actuators described herein.

A control system may be provided in conjunction with the hydraulicsystem 2420 to control operation of the lift actuator 2416 according toone embodiment of the method 3000. The control system may be integratedwith control aspects of the hydraulic system 2420 in the illustratedembodiment; however, it is to be understood that the control system maybe separate.

The control system may include any and all electrical circuitry andcomponents to carry out the functions and algorithms described herein.Generally speaking, the control system may include one or moremicrocontrollers, microprocessors, and/or other programmable electronicsthat are programmed to carry out the functions described herein. Thecontrol system may additionally or alternatively include otherelectronic components that are programmed to carry out the functionsdescribed herein, or that support the microcontrollers, microprocessors,and/or other electronics. The other electronic components include, butare not limited to, one or more field programmable gate arrays (FPGAs),systems on a chip, volatile or nonvolatile memory, discrete circuitry,integrated circuits, application specific integrated circuits (ASICs)and/or other hardware, software, or firmware. Such components can bephysically configured in any suitable manner, such as by mounting themto one or more circuit boards, or arranging them in other manners,whether combined into a single unit or distributed across multipleunits. Such components may be physically distributed in differentpositions, or they may reside in a common location. When physicallydistributed, the components may communicate using any suitable serial orparallel communication protocol, such as, but not limited to, CAN, LIN,FireWire, I2C, RS-232, RS-485, and Universal Serial Bus (USB).

The control system for the method 3000 may operate a pneumatic valve2413 disposed between the accumulator 2417 and the lift actuator 2416,and more specifically between the accumulator 2417 and a lift actuatorreservoir 2411 of the lift actuator 2416. The pneumatic valve 2413 mayoptionally include an orifice that restricts flow of gas from theaccumulator 2417 to the lift actuator reservoir. Additionally, with thepneumatic valve 2413 including such an orifice, a second pneumatic valvemay be disposed in parallel with the pneumatic valve 2413 and configuredto selectively provide unrestricted flow of gas between the accumulator2417 and the lift actuator reservoir 2411. For instance, the pneumaticvalve 2413 with a restricting orifice may be operated for timed controlin accordance with steps 3004 and 3008 described herein, and the secondpneumatic valve may be operated for control with full pressure inaccordance with steps 3004 and 3006.

The lift actuator reservoir 2411 may be configured to containcompressible gas. Compressible gas may be added to or removed from thelift actuator reservoir 2411 in accordance with the method 3000. Forinstance, the control system may operate the pneumatic valve 2413 toprovide compressible gas from the accumulator 2417 to the lift actuatorreservoir 2411, and compressible gas may be transferred from the liftactuator reservoir 2411 via a check valve 2418.

The check valve 2418 may limit a pressure of the lift actuator reservoir2411 to be less than or equal to the pressure of compressible gas in theaccumulator 2417.

In the illustrated embodiment, from step 3006 to step 3012, thepneumatic valve 2413 may be closed and hydraulic fluid may be providedfrom the hydraulic system 2420 to the lift actuator 2416 via operationof a hydraulic valve 2423 in order to retract the lift actuator 2416. Inthis sequence, with a starting pressure of the lift actuator reservoir2411 being pressure p, the same as the pressure p of the accumulator2417, the decrease in volume of the lift actuator reservoir 2411 due toapplication of hydraulic pressure causes the pressure in the liftactuator reservoir 2411 to rise. The check valve 2418 may open to limitpressure in the lift actuator reservoir 2411 such that, at the retractedposition, the pressure of the lift actuator reservoir 2411 issubstantially the same as the pressure p of the accumulator 2417 despitethe change in volume of the lift actuator reservoir 2411. In thissequence, because the initial pressure of the lift actuator 2411 is p ornearly the same as the pressure p of the accumulator 2417, the pressurein the lift actuator reservoir 2411 may exceed the pressure p soon afterhydraulic pressure is applied to the lift actuator 2416, such that theopen check valve 2414 may open soon after hydraulic pressure is appliedto the lift actuator 2416.

In other sequences, such as a transition from an extended position witha pressure in the lift actuator reservoir 2411 being less than thepressure p of the accumulator 2417 (e.g., from step 3008 to step 3012and then to step 3002), the pressure of the lift actuator reservoir 2411may cause the check valve 2418 to open midway between the retracted andextended position or closer to the retracted position.

In one embodiment, at step 3010, the pressure of the lift actuatorreservoir 2411 at the extended position may correspond solely to achange in volume of the lift actuator reservoir 2411 due to movementfrom the retracted position to the extended position. In other words, asdepicted in the illustrated embodiment, from steps 3002 to step 3004 andto step 3010, the pneumatic valve 2413 may be kept closed such that thepressure change in the lift actuator reservoir 2411 corresponds to achange in volume and not a change in amount of compressible gas. As aresult, retraction of the lift actuator 2416 from the extended positionto the retracted position may return a pressure of the lift actuatorreservoir 2411 to a pressure p similar to or the same as the pressure pof the accumulator 2417 without opening the check valve 2418.

The lift actuator reservoir 2411 in the illustrated embodiment isvariable in size, depending on the position of the lift actuator 2416.As an example, the volume of the lift actuator reservoir 2411 with thelift actuator 2416 in a retracted position (e.g., step 3002) is lessthan a volume of the lift actuator reservoir 2411 with the lift actuator2416 in an extended position (e.g., step 3006). As a result, a pressureof compressible gas in the lift actuator reservoir 2411 may be variedbased on a position of the lift actuator 2416, timing of operation ofthe pneumatic valve 2413 for supply of compressible gas at pressure p tothe lift actuator reservoir 2411, and operation of the check valve 2418to limit pressure

Starting at step 3002, with the lift actuator 2416 in a retractedposition, the hydraulic system 2420 may operate a hydraulic valve 2428to transition from applying hydraulic pressure to a float mode to allowthe lift actuator 2416 to begin extending to the extended position. Step3004. Depending on the configuration, a transition to float mode for thehydraulic system 2420 may be sufficient to enable extension of the liftactuator 2416 (or another actuator described herein) due at least inpart to a weight of the plow 2000 coupled to the lift actuator 2416. Anincrease in pressure of the lift actuator reservoir 2411 via opening thepneumatic valve 2413 may also facilitate extension of the lift actuator2416.

During or after extension of the lift actuator, the pneumatic valve 2413may be opened to control a pressure of the lift actuator reservoir 2411.Depending on a pressure of the lift actuator reservoir 2411, asdescribed herein, a bias force F_(d) may be present for biasing the liftactuator 2416 toward the extended position. In the context of the liftactuator 2416, the bias force F_(d) may correspond to downforce appliedon the plow 1000 toward contact with the ground.

At step 3010, as described herein, the control system may keep thepneumatic valve 2413 in a closed position as the hydraulic system 2420transitions to a float mode and allows the lift actuator 2416 to extend.The pressure of the lift actuator reservoir 2411 in this configurationmay be significantly less than the pressure p of the accumulator 2417due to the increase in size of the lift actuator reservoir 2411. Forinstance, the pressure of the lift actuator reservoir 2411 may decreasefrom a pressure p of 600 psi in the accumulator 2417 to a pressure of100 psi in the lift actuator reservoir 2411 with the lift actuator 2416at full extension. This configuration may provide little or no biasforce F_(d) toward extension (e.g., little or no downforce applied tothe plow 2000). With little or no bias force F_(d), and the hydraulicsystem 2420 in a float mode, the lift actuator 2416 may enable the plow2000 to raise and lower without substantial downforce applied to theplow 2000 toward contact with the ground.

At step 3006, as described herein, the control system may maintain thepneumatic valve 2413 in an open position to enable gaseous communicationbetween the accumulator 2417 and the lift actuator reservoir 2416. As aresult, a pressure of the lift actuator reservoir 2416 may substantiallycorrespond to a pressure p of the accumulator 2417 present at step 3002.The volume of the accumulator 2417 may be substantially larger than thevolume of the lift actuator reservoir 2416, so that transfer ofcompressible gas from the accumulator 2417 to the lift actuatorreservoir 2416 has a reduced or de minimus effect on pressure p of theaccumulator 2417 and the overall system.

In the illustrated embodiment, at step 3006, the bias force F_(d) towardextension of the actuator 2416 is a function of the pressure p of thelift actuator reservoir 2411. This bias force Fd may be the maximumallowable by the system, and may provide downforce with respect to thesnow plow 2000 and the ground. If an obstruction is encountered thatcounters and exceeds the downforce, the lift actuator 2416 may retractas the compressible gas is compressed and the pressure in theaccumulator 2417 and the lift actuator reservoir 2411 increases. Inresponse to the obstruction force, the gas may compress until the liftactuator 2416 bottoms out or full retracts or until compression of thegas generates a bias force Fd that is in equilibrium with theobstruction force applied on the lift actuator 2416. After theobstruction force recedes, the compressible gas may extend the liftactuator 2416 back toward extension to bias the snow plow 2000 towardthe ground.

In an alternative embodiment of step 3006, the control system may openthe pneumatic valve 2413 to pressurize the lift actuator reservoir 2416in the fully extended position at pressure p of the accumulator 2417.However, at this stage, the control system may close the pneumatic valve2413 so that the lift actuator reservoir 2411 is not coupled to theaccumulator 2417 via the pneumatic valve 2413. The lift actuator 2416 inthis configuration may apply a bias force F_(d) similar to thatdescribed above in conjunction with step 3006 and the pneumatic valve2413 being maintained in an open position. However, in response toencountering an obstruction force that exceeds the bias force F_(d), gasin the lift actuator reservoir 2411 may begin to compress and open thecheck valve 2418, bleeding or transferring gas from the lift actuatorreservoir 2411 to the accumulator 2417. After the obstruction forcerecedes, the check valve 2418 may be closed, the lift actuator 2416 mayextend but the bias force toward extension may be less because thepressure in the lift actuator reservoir 2411 deceases due to expansionin the volume of the lift actuator reservoir 2411.

In the illustrated embodiment, at step 3008, the lift actuator 2416 maybe extended. The control system may operate the pneumatic valve 2413 tocontrol a pressure of the lift actuator reservoir 2411. The controlsystem may open the pneumatic valve 2413 during extension of the liftactuator 2416 or after extension of the lift actuator 2416. The pressureof the lift actuator reservoir 2411 may be controlled in accordance witha duration (e.g., a length of time) of activation of the pneumatic valve2413 (e.g., 0.5 s, 1.0 s, 1.5 s, 2.0 s). For instance, the controlsystem may be configured to open the pneumatic valve for 0.5 s to raisethe pressure of the lift actuator reservoir 2411 from 100 to 200 psi(relative to step 3010) with the lift actuator 2416 in the extendedposition. This configuration provides an open loop type of control ofthe pressure in the lift actuator reservoir 2411. In one embodiment, anoperator may direct the control system to open the pneumatic valve 2413to increase the pressure in the lift actuator reservoir 2411 in order toincrease a downforce on the plow 2000. The operator may bump or actuatethe pneumatic valve 2413 one or more times until a pressure is achievedto the satisfaction of the operator.

Alternatively, a sensor may be provided that provides sensor outputindicative of a pressure of the lift actuator reservoir 2411. Thecontrol system may be operable to receive this sensor output and tocontrol the pneumatic valve 2413 based on the sensor output to control apressure of the lift actuator reservoir 2411 according to a targetpressure selected by the system and/or an operator.

By controlling the pressure of the lift actuator reservoir 2411 (e.g.,open loop or closed loop), the control system can control the amount ofbias force F_(d) generated by the lift actuator 2416 toward the extendedposition. In other words, a system in accordance with one embodiment mayprovide variable downforce or down pressure with respect to the snowplow 2000 and the ground.

At step 3008, if an obstruction force exceeds the bias force F_(d), thelift actuator 2416 may retract until the lift actuator 2416 is fullyretracted or an equilibrium is satisfied between the increase inpressure and resulting increase in bias force F_(d) and the obstructionforce. If the pressure in the lift actuator reservoir 2411 exceeds thepressure p of the accumulator 2417, the check valve 2418 may open tobleed or transfer gas from the lift actuator reservoir 2411 to theaccumulator 2417 so that the pressure of the lift actuator reservoir2411 does not significantly exceed the pressure p of the accumulator2417. After the obstruction force is removed, the lift actuator 2416 mayextend, and depending on whether the check valve 2418 opened, the biasforce F_(d) may be the same or less than before the obstruction wasencountered. The control system may be automatic or in response to inputfrom an operator opening the pneumatic valve 2413 to supply compressiblegas to the lift actuator reservoir 2411.

As described herein, the method 3000 may involve the hydraulic system2420 transitioning from a float mode to a pressure mode to supplyhydraulic fluid to the lift actuator 2416 under pressure and retract thelift actuator 2416. The pressure in the lift actuator reservoir 2411 maybe limited to the pressure p of the accumulator 2417 by the check valve2418. It is noted that the operation of the hydraulic system 2420 andthe control system in accordance with the method 3000 may be based atleast in part on input or directive from the operator (e.g., a directiveto lower or raise the snow plow 2000.). Directional terms, such as“vertical,” “horizontal,” “top,” “bottom,” “upper,” “lower,” “inner,”“inwardly,” “outer” and “outwardly,” are used to assist in describingthe invention based on the orientation of the embodiments shown in theillustrations. The use of directional terms should not be interpreted tolimit the invention to any specific orientation(s).

The above description is that of current embodiments of the invention.Various alterations and changes can be made without departing from thespirit and broader aspects of the invention as defined in the appendedclaims, which are to be interpreted in accordance with the principles ofpatent law including the doctrine of equivalents. This disclosure ispresented for illustrative purposes and should not be interpreted as anexhaustive description of all embodiments of the invention or to limitthe scope of the claims to the specific elements illustrated ordescribed in connection with these embodiments. For example, and withoutlimitation, any individual element(s) of the described invention may bereplaced by alternative elements that provide substantially similarfunctionality or otherwise provide adequate operation. This includes,for example, presently known alternative elements, such as those thatmight be currently known to one skilled in the art, and alternativeelements that may be developed in the future, such as those that oneskilled in the art might, upon development, recognize as an alternative.Further, the disclosed embodiments include a plurality of features thatare described in concert and that might cooperatively provide acollection of benefits. The present invention is not limited to onlythose embodiments that include all of these features or that provide allof the stated benefits, except to the extent otherwise expressly setforth in the issued claims. Any reference to claim elements in thesingular, for example, using the articles “a,” “an,” “the” or “said,” isnot to be construed as limiting the element to the singular. Anyreference to claim elements as “at least one of X, Y and Z” is meant toinclude any one of X, Y or Z individually, and any combination of X, Yand Z, for example, X, Y, Z; X, Y; X, Z; and Y, Z.

1. A linkage for a snow plow comprising: a cylinder including a firstcylinder end and a second cylinder end; a piston movable within thecylinder between the first cylinder end and the second cylinder end; arod coupled to the piston, the rod including a rod end movable relativeto the second cylinder end; and a compressible gas in contact with thepiston and operable to bias the piston and the rod such that the linkagebiases a plow portion of the snow plow to a bias position, wherein thecylinder is operable to receive hydraulic fluid to move the piston andthe rod such that the plow portion of the snow plow moves away from thebias position.
 2. The linkage of claim 1 wherein the linkage is coupledto an accumulator operable to store compressible gas and in fluidcommunication with the compressible gas of the linkage.
 3. The linkageof claim 1 wherein the rod end is coupled to the plow portion of thesnow plow.
 4. The linkage of claim 1 wherein the compressible gas biasesthe rod end away from the second cylinder end to bias the linkage towardan extended position.
 5. The linkage of claim 4 wherein the hydraulicfluid is operable to move the rod end toward the second cylinder end tomove the linkage toward a retracted position.
 6. The linkage of claim 1wherein the plow portion is a blade of the snow plow.
 7. The linkage ofclaim 1 wherein the linkage is operably coupled to a control system,wherein the control system is configured to direct supply of hydraulicfluid to the cylinder.
 8. The linkage of claim 1 wherein the linkage isan actuator operable to move the plow portion of the snow plow from afirst position to a second position.
 9. A snow plow assembly includingthe linkage of claim 1, the snow plow assembly comprising: a bladeoperable to contact a ground surface to facilitate moving snow, theblade coupled to one end the linkage; a plow support coupled to anopposite end of the linkage; a vehicle support removably coupled to theplow support; and a control system operably coupled to the linkage, thecontrol system configured to direct the linkage to move the blade from afirst position to a second position, the control system configured todirect supply of hydraulic fluid to the actuator.
 10. The snow plowassembly of claim 9 wherein the linkage is coupled to the blade via aconnection that is maintained by a pin.
 11. The snow plow assembly ofclaim 10 wherein the snow plow includes multiple connection points forconnecting the linkage to the snow plow via the pin.
 12. The snow plowof claim 9 wherein the linkage is operable to automatically retract inresponse to application of force on blade.
 13. A method of operating alinkage for a snow plow, the method comprising: providing a cylinder anda piston within the cylinder that is movable between a first cylinderend and a second cylinder end, wherein a plow portion of the snow plowis coupled to the piston via a rod; expanding compressible gas againstthe piston to move the piston from the first cylinder end to the secondcylinder end such that the plow portion is moved via movement of thepiston and the rod; and supplying hydraulic fluid into the cylinder tomove the piston from the second cylinder end to the first cylinder endsuch that the plow portion is moved via movement of the piston and therod.
 14. The method of claim 13 comprising: providing an accumulator influid communication with the cylinder; and receiving compressible gas inthe accumulator from the cylinder.
 15. The method of claim 13 whereinthe plow portion is coupled to the plow portion of the snow plow. 16.The method of claim 13 comprising biasing, via expansion of compressiblegas, a rod end of the rod away from the second cylinder end.
 17. Themethod of claim 13 wherein said supplying hydraulic fluid includescompressing the compressible gas via movement of the piston from thesecond cylinder end to the first cylinder end.
 18. The method of claim13 wherein said supplying hydraulic fluid includes supplying hydraulicfluid to a side of the cylinder proximal to the second cylinder end. 19.The method of claim 13 comprising connecting the rod to a connector ofthe snow plow via a pin.
 20. The method of claim 19 comprising moving aconnection to the snow plow via removal and reinstallation of the pin ata different location with respect to the snow plow.